fix(mcp): Integrate MCPToolBlock with standard credentials system

- Replace manual credential_id field with CredentialsMetaInput pattern
- Fix credential deduplication so different MCP server URLs get separate
  credential entries in the task credentials panel
- Add descriptive display names (e.g. "MCP: mcp.sentry.dev")
- Fix OAuth popup callback by adding mcp_callback route to middleware
  exclusion list and adding localStorage polling fallback
- Fix SSRF test fixture to patch Requests constructor directly
- Add MCP server URL matching for credential auto-assignment
- Return CredentialsMetaResponse from MCP OAuth callback
- Support MCP-specific OAuth flow in frontend credential input
- Filter MCP credentials by server URL in frontend
- Add test coverage for credential deduplication logic

autogpt_platform/backend/MCP_BLOCK_IMPLEMENTATION.md

@@ -0,0 +1,76 @@
+# MCP Block Implementation Plan
+
+## Overview
+
+Create a single **MCPBlock** that dynamically integrates with any MCP (Model Context Protocol)
+server. Users provide a server URL, the block discovers available tools, presents them as a
+dropdown, and dynamically adjusts input/output schema based on the selected tool — exactly like
+`AgentExecutorBlock` handles dynamic schemas.
+
+## Architecture
+
+```
+User provides MCP server URL + credentials
+         ↓
+MCPBlock fetches tools via MCP protocol (tools/list)
+         ↓
+User selects tool from dropdown (stored in constantInput)
+         ↓
+Input schema dynamically updates based on selected tool's inputSchema
+         ↓
+On execution: MCPBlock calls the tool via MCP protocol (tools/call)
+         ↓
+Result yielded as block output
+```
+
+## Design Decisions
+
+1. **Single block, not many blocks** — One `MCPBlock` handles all MCP servers/tools
+2. **Dynamic schema via AgentExecutorBlock pattern** — Override `get_input_schema()`,
+   `get_input_defaults()`, `get_missing_input()` on the Input class
+3. **Auth via API key or OAuth2 credentials** — Use existing `APIKeyCredentials` or
+   `OAuth2Credentials` with `ProviderName.MCP` provider. API keys are sent as Bearer tokens;
+   OAuth2 uses the access token.
+4. **HTTP-based MCP client** — Use `aiohttp` (already a dependency) to implement MCP Streamable
+   HTTP transport directly. No need for the `mcp` Python SDK — the protocol is simple JSON-RPC
+   over HTTP. Handles both JSON and SSE response formats.
+5. **No new DB tables** — Everything fits in existing `AgentBlock` + `AgentNode` tables
+
+## Implementation Files
+
+### New Files
+- `backend/blocks/mcp/` — MCP block package
+  - `__init__.py`
+  - `block.py` — MCPToolBlock implementation
+  - `client.py` — MCP HTTP client (list_tools, call_tool)
+  - `oauth.py` — MCP OAuth handler for dynamic endpoint discovery
+  - `test_mcp.py` — Unit tests
+  - `test_oauth.py` — OAuth handler tests
+  - `test_integration.py` — Integration tests with local test server
+  - `test_e2e.py` — E2E tests against real MCP servers
+
+### Modified Files
+- `backend/integrations/providers.py` — Add `MCP = "mcp"` to ProviderName
+
+## Dev Loop
+
+```bash
+cd autogpt_platform/backend
+poetry run pytest backend/blocks/mcp/test_mcp.py -xvs        # Unit tests
+poetry run pytest backend/blocks/mcp/test_oauth.py -xvs       # OAuth tests
+poetry run pytest backend/blocks/mcp/test_integration.py -xvs  # Integration tests
+poetry run pytest backend/blocks/mcp/ -xvs                     # All MCP tests
+```
+
+## Status
+
+- [x] Research & Design
+- [x] Add ProviderName.MCP
+- [x] Implement MCP client (client.py)
+- [x] Implement MCPToolBlock (block.py)
+- [x] Add OAuth2 support (oauth.py)
+- [x] Write unit tests
+- [x] Write integration tests
+- [x] Write E2E tests
+- [x] Run tests & fix issues
+- [x] Create PR

autogpt_platform/backend/backend/api/features/chat/tools/utils.py

@@ -8,12 +8,14 @@ from backend.api.features.library import model as library_model
 from backend.api.features.store import db as store_db
 from backend.data.graph import GraphModel
 from backend.data.model import (
+    Credentials,
     CredentialsFieldInfo,
     CredentialsMetaInput,
     HostScopedCredentials,
     OAuth2Credentials,
 )
 from backend.integrations.creds_manager import IntegrationCredentialsManager
+from backend.integrations.providers import ProviderName
 from backend.util.exceptions import NotFoundError
 
 logger = logging.getLogger(__name__)
@@ -265,7 +267,7 @@ async def match_user_credentials_to_graph(
         _,
         _,
     ) in aggregated_creds.items():
-        # Find first matching credential by provider, type, and scopes
+        # Find first matching credential by provider, type, scopes, and host/URL
         matching_cred = next(
             (
                 cred
@@ -280,6 +282,10 @@ async def match_user_credentials_to_graph(
                     cred.type != "host_scoped"
                     or _credential_is_for_host(cred, credential_requirements)
                 )
+                and (
+                    cred.provider != ProviderName.MCP
+                    or _credential_is_for_mcp_server(cred, credential_requirements)
+                )
             ),
             None,
         )
@@ -352,6 +358,22 @@ def _credential_is_for_host(
     return credential.matches_url(list(requirements.discriminator_values)[0])
 
 
+def _credential_is_for_mcp_server(
+    credential: Credentials,
+    requirements: CredentialsFieldInfo,
+) -> bool:
+    """Check if an MCP OAuth credential matches the required server URL."""
+    if not requirements.discriminator_values:
+        return True
+
+    server_url = (
+        credential.metadata.get("mcp_server_url")
+        if isinstance(credential, OAuth2Credentials)
+        else None
+    )
+    return server_url in requirements.discriminator_values if server_url else False
+
+
 async def check_user_has_required_credentials(
     user_id: str,
     required_credentials: list[CredentialsMetaInput],

autogpt_platform/backend/backend/api/features/integrations/router.py

@@ -102,9 +102,19 @@ class CredentialsMetaResponse(BaseModel):
     scopes: list[str] | None
     username: str | None
     host: str | None = Field(
-        default=None, description="Host pattern for host-scoped credentials"
+        default=None,
+        description="Host pattern for host-scoped or MCP server URL for MCP credentials",
     )
 
+    @staticmethod
+    def get_host(cred: Credentials) -> str | None:
+        """Extract host from credential: HostScoped host or MCP server URL."""
+        if isinstance(cred, HostScopedCredentials):
+            return cred.host
+        if isinstance(cred, OAuth2Credentials) and cred.provider == ProviderName.MCP:
+            return (cred.metadata or {}).get("mcp_server_url")
+        return None
+
 
 @router.post("/{provider}/callback", summary="Exchange OAuth code for tokens")
 async def callback(
@@ -179,9 +189,7 @@ async def callback(
         title=credentials.title,
         scopes=credentials.scopes,
         username=credentials.username,
-        host=(
+        host=(CredentialsMetaResponse.get_host(credentials)),
-            credentials.host if isinstance(credentials, HostScopedCredentials) else None
-        ),
     )
 
 
@@ -199,7 +207,7 @@ async def list_credentials(
             title=cred.title,
             scopes=cred.scopes if isinstance(cred, OAuth2Credentials) else None,
             username=cred.username if isinstance(cred, OAuth2Credentials) else None,
-            host=cred.host if isinstance(cred, HostScopedCredentials) else None,
+            host=CredentialsMetaResponse.get_host(cred),
         )
         for cred in credentials
     ]
@@ -222,7 +230,7 @@ async def list_credentials_by_provider(
             title=cred.title,
             scopes=cred.scopes if isinstance(cred, OAuth2Credentials) else None,
             username=cred.username if isinstance(cred, OAuth2Credentials) else None,
-            host=cred.host if isinstance(cred, HostScopedCredentials) else None,
+            host=CredentialsMetaResponse.get_host(cred),
         )
         for cred in credentials
     ]

autogpt_platform/backend/backend/api/features/mcp/routes.py

@@ -0,0 +1,412 @@
+"""
+MCP (Model Context Protocol) API routes.
+
+Provides endpoints for MCP tool discovery and OAuth authentication so the
+frontend can list available tools on an MCP server before placing a block.
+"""
+
+import logging
+from typing import Annotated, Any
+from urllib.parse import urlparse
+
+import fastapi
+from autogpt_libs.auth import get_user_id
+from fastapi import Security
+from pydantic import BaseModel, Field
+
+from backend.api.features.integrations.router import CredentialsMetaResponse
+from backend.blocks.mcp.client import MCPClient, MCPClientError
+from backend.blocks.mcp.oauth import MCPOAuthHandler
+from backend.data.model import OAuth2Credentials
+from backend.integrations.creds_manager import IntegrationCredentialsManager
+from backend.integrations.providers import ProviderName
+from backend.util.request import HTTPClientError, Requests
+from backend.util.settings import Settings
+
+logger = logging.getLogger(__name__)
+
+settings = Settings()
+router = fastapi.APIRouter(tags=["mcp"])
+creds_manager = IntegrationCredentialsManager()
+
+
+# ====================== Tool Discovery ====================== #
+
+
+class DiscoverToolsRequest(BaseModel):
+    """Request to discover tools on an MCP server."""
+
+    server_url: str = Field(description="URL of the MCP server")
+    auth_token: str | None = Field(
+        default=None,
+        description="Optional Bearer token for authenticated MCP servers",
+    )
+
+
+class MCPToolResponse(BaseModel):
+    """A single MCP tool returned by discovery."""
+
+    name: str
+    description: str
+    input_schema: dict[str, Any]
+
+
+class DiscoverToolsResponse(BaseModel):
+    """Response containing the list of tools available on an MCP server."""
+
+    tools: list[MCPToolResponse]
+    server_name: str | None = None
+    protocol_version: str | None = None
+
+
+@router.post(
+    "/discover-tools",
+    summary="Discover available tools on an MCP server",
+    response_model=DiscoverToolsResponse,
+)
+async def discover_tools(
+    request: DiscoverToolsRequest,
+    user_id: Annotated[str, Security(get_user_id)],
+) -> DiscoverToolsResponse:
+    """
+    Connect to an MCP server and return its available tools.
+
+    If the user has a stored MCP credential for this server URL, it will be
+    used automatically — no need to pass an explicit auth token.
+    """
+    auth_token = request.auth_token
+
+    # Auto-use stored MCP credential when no explicit token is provided
+    if not auth_token:
+        try:
+            mcp_creds = await creds_manager.store.get_creds_by_provider(
+                user_id, str(ProviderName.MCP)
+            )
+            # Find the freshest credential for this server URL
+            best_cred: OAuth2Credentials | None = None
+            for cred in mcp_creds:
+                if (
+                    isinstance(cred, OAuth2Credentials)
+                    and cred.metadata.get("mcp_server_url") == request.server_url
+                ):
+                    if best_cred is None or (
+                        (cred.access_token_expires_at or 0)
+                        > (best_cred.access_token_expires_at or 0)
+                    ):
+                        best_cred = cred
+            if best_cred:
+                logger.info(
+                    f"Using MCP credential {best_cred.id} for {request.server_url}, "
+                    f"expires_at={best_cred.access_token_expires_at}"
+                )
+                auth_token = best_cred.access_token.get_secret_value()
+        except Exception:
+            logger.debug("Could not look up stored MCP credentials", exc_info=True)
+
+    try:
+        client = MCPClient(request.server_url, auth_token=auth_token)
+
+        init_result = await client.initialize()
+        tools = await client.list_tools()
+
+        return DiscoverToolsResponse(
+            tools=[
+                MCPToolResponse(
+                    name=t.name,
+                    description=t.description,
+                    input_schema=t.input_schema,
+                )
+                for t in tools
+            ],
+            server_name=init_result.get("serverInfo", {}).get("name"),
+            protocol_version=init_result.get("protocolVersion"),
+        )
+    except HTTPClientError as e:
+        if e.status_code in (401, 403):
+            logger.warning(
+                f"MCP server returned {e.status_code} for {request.server_url}: {e}"
+            )
+            raise fastapi.HTTPException(
+                status_code=401,
+                detail="This MCP server requires authentication. "
+                "Please provide a valid auth token.",
+            )
+        raise fastapi.HTTPException(status_code=502, detail=str(e))
+    except MCPClientError as e:
+        raise fastapi.HTTPException(status_code=502, detail=str(e))
+    except Exception as e:
+        logger.exception("MCP tool discovery failed")
+        raise fastapi.HTTPException(
+            status_code=502,
+            detail=f"Failed to connect to MCP server: {str(e)}",
+        )
+
+
+# ======================== OAuth Flow ======================== #
+
+
+class MCPOAuthLoginRequest(BaseModel):
+    """Request to start an OAuth flow for an MCP server."""
+
+    server_url: str = Field(description="URL of the MCP server that requires OAuth")
+
+
+class MCPOAuthLoginResponse(BaseModel):
+    """Response with the OAuth login URL for the user to authenticate."""
+
+    login_url: str
+    state_token: str
+
+
+@router.post(
+    "/oauth/login",
+    summary="Initiate OAuth login for an MCP server",
+)
+async def mcp_oauth_login(
+    request: MCPOAuthLoginRequest,
+    user_id: Annotated[str, Security(get_user_id)],
+) -> MCPOAuthLoginResponse:
+    """
+    Discover OAuth metadata from the MCP server and return a login URL.
+
+    1. Discovers the protected-resource metadata (RFC 9728)
+    2. Fetches the authorization server metadata (RFC 8414)
+    3. Performs Dynamic Client Registration (RFC 7591) if available
+    4. Returns the authorization URL for the frontend to open in a popup
+    """
+    client = MCPClient(request.server_url)
+
+    # Step 1: Discover protected-resource metadata (RFC 9728)
+    try:
+        protected_resource = await client.discover_auth()
+    except Exception as e:
+        raise fastapi.HTTPException(
+            status_code=502,
+            detail=f"Failed to discover OAuth metadata: {e}",
+        )
+
+    metadata: dict[str, Any] | None = None
+
+    if protected_resource and "authorization_servers" in protected_resource:
+        auth_server_url = protected_resource["authorization_servers"][0]
+        resource_url = protected_resource.get("resource", request.server_url)
+
+        # Step 2a: Discover auth-server metadata (RFC 8414)
+        try:
+            metadata = await client.discover_auth_server_metadata(auth_server_url)
+        except Exception as e:
+            raise fastapi.HTTPException(
+                status_code=502,
+                detail=f"Failed to discover authorization server metadata: {e}",
+            )
+    else:
+        # Fallback: Some MCP servers (e.g. Linear) are their own auth server
+        # and serve OAuth metadata directly without protected-resource metadata.
+        # Don't assume a resource_url — omitting it lets the auth server choose
+        # the correct audience for the token (RFC 8707 resource is optional).
+        resource_url = None
+        try:
+            metadata = await client.discover_auth_server_metadata(request.server_url)
+        except Exception:
+            pass
+
+    if not metadata or "authorization_endpoint" not in metadata:
+        raise fastapi.HTTPException(
+            status_code=400,
+            detail="This MCP server does not advertise OAuth support. "
+            "You may need to provide an auth token manually.",
+        )
+
+    authorize_url = metadata["authorization_endpoint"]
+    token_url = metadata["token_endpoint"]
+    registration_endpoint = metadata.get("registration_endpoint")
+    revoke_url = metadata.get("revocation_endpoint")
+
+    # Step 3: Dynamic Client Registration (RFC 7591) if available
+    frontend_base_url = settings.config.frontend_base_url
+    if not frontend_base_url:
+        raise fastapi.HTTPException(
+            status_code=500,
+            detail="Frontend base URL is not configured.",
+        )
+    redirect_uri = f"{frontend_base_url}/auth/integrations/mcp_callback"
+
+    client_id = ""
+    client_secret = ""
+    if registration_endpoint:
+        reg_result = await _register_mcp_client(
+            registration_endpoint, redirect_uri, request.server_url
+        )
+        if reg_result:
+            client_id = reg_result.get("client_id", "")
+            client_secret = reg_result.get("client_secret", "")
+
+    if not client_id:
+        client_id = "autogpt-platform"
+
+    # Step 4: Store state token with OAuth metadata for the callback
+    scopes = (protected_resource or {}).get("scopes_supported") or metadata.get(
+        "scopes_supported", []
+    )
+    state_token, code_challenge = await creds_manager.store.store_state_token(
+        user_id,
+        str(ProviderName.MCP),
+        scopes,
+        state_metadata={
+            "authorize_url": authorize_url,
+            "token_url": token_url,
+            "revoke_url": revoke_url,
+            "resource_url": resource_url,
+            "server_url": request.server_url,
+            "client_id": client_id,
+            "client_secret": client_secret,
+        },
+    )
+
+    # Step 5: Build and return the login URL
+    handler = MCPOAuthHandler(
+        client_id=client_id,
+        client_secret=client_secret,
+        redirect_uri=redirect_uri,
+        authorize_url=authorize_url,
+        token_url=token_url,
+        resource_url=resource_url,
+    )
+    login_url = handler.get_login_url(
+        scopes, state_token, code_challenge=code_challenge
+    )
+
+    return MCPOAuthLoginResponse(login_url=login_url, state_token=state_token)
+
+
+class MCPOAuthCallbackRequest(BaseModel):
+    """Request to exchange an OAuth code for tokens."""
+
+    code: str = Field(description="Authorization code from OAuth callback")
+    state_token: str = Field(description="State token for CSRF verification")
+
+
+class MCPOAuthCallbackResponse(BaseModel):
+    """Response after successfully storing OAuth credentials."""
+
+    credential_id: str
+
+
+@router.post(
+    "/oauth/callback",
+    summary="Exchange OAuth code for MCP tokens",
+)
+async def mcp_oauth_callback(
+    request: MCPOAuthCallbackRequest,
+    user_id: Annotated[str, Security(get_user_id)],
+) -> CredentialsMetaResponse:
+    """
+    Exchange the authorization code for tokens and store the credential.
+
+    The frontend calls this after receiving the OAuth code from the popup.
+    On success, subsequent ``/discover-tools`` calls for the same server URL
+    will automatically use the stored credential.
+    """
+    valid_state = await creds_manager.store.verify_state_token(
+        user_id, request.state_token, str(ProviderName.MCP)
+    )
+    if not valid_state:
+        raise fastapi.HTTPException(
+            status_code=400,
+            detail="Invalid or expired state token.",
+        )
+
+    meta = valid_state.state_metadata
+    frontend_base_url = settings.config.frontend_base_url
+    redirect_uri = f"{frontend_base_url}/auth/integrations/mcp_callback"
+
+    handler = MCPOAuthHandler(
+        client_id=meta["client_id"],
+        client_secret=meta.get("client_secret", ""),
+        redirect_uri=redirect_uri,
+        authorize_url=meta["authorize_url"],
+        token_url=meta["token_url"],
+        revoke_url=meta.get("revoke_url"),
+        resource_url=meta.get("resource_url"),
+    )
+
+    try:
+        credentials = await handler.exchange_code_for_tokens(
+            request.code, valid_state.scopes, valid_state.code_verifier
+        )
+    except Exception as e:
+        logger.exception("MCP OAuth token exchange failed")
+        raise fastapi.HTTPException(
+            status_code=400,
+            detail=f"OAuth token exchange failed: {e}",
+        )
+
+    # Enrich credential metadata for future lookup and token refresh
+    if credentials.metadata is None:
+        credentials.metadata = {}
+    credentials.metadata["mcp_server_url"] = meta["server_url"]
+    credentials.metadata["mcp_client_id"] = meta["client_id"]
+    credentials.metadata["mcp_client_secret"] = meta.get("client_secret", "")
+    credentials.metadata["mcp_token_url"] = meta["token_url"]
+    credentials.metadata["mcp_resource_url"] = meta.get("resource_url", "")
+
+    hostname = urlparse(meta["server_url"]).hostname or meta["server_url"]
+    credentials.title = f"MCP: {hostname}"
+
+    # Remove old MCP credentials for the same server to prevent stale token buildup
+    try:
+        old_creds = await creds_manager.store.get_creds_by_provider(
+            user_id, str(ProviderName.MCP)
+        )
+        for old in old_creds:
+            if (
+                isinstance(old, OAuth2Credentials)
+                and old.metadata.get("mcp_server_url") == meta["server_url"]
+            ):
+                await creds_manager.store.delete_creds_by_id(user_id, old.id)
+                logger.info(
+                    f"Removed old MCP credential {old.id} for {meta['server_url']}"
+                )
+    except Exception:
+        logger.debug("Could not clean up old MCP credentials", exc_info=True)
+
+    await creds_manager.create(user_id, credentials)
+
+    return CredentialsMetaResponse(
+        id=credentials.id,
+        provider=credentials.provider,
+        type=credentials.type,
+        title=credentials.title,
+        scopes=credentials.scopes,
+        username=credentials.username,
+        host=credentials.metadata.get("mcp_server_url"),
+    )
+
+
+# ======================== Helpers ======================== #
+
+
+async def _register_mcp_client(
+    registration_endpoint: str,
+    redirect_uri: str,
+    server_url: str,
+) -> dict[str, Any] | None:
+    """Attempt Dynamic Client Registration (RFC 7591) with an MCP auth server."""
+    try:
+        response = await Requests(raise_for_status=True).post(
+            registration_endpoint,
+            json={
+                "client_name": "AutoGPT Platform",
+                "redirect_uris": [redirect_uri],
+                "grant_types": ["authorization_code"],
+                "response_types": ["code"],
+                "token_endpoint_auth_method": "client_secret_post",
+            },
+        )
+        data = response.json()
+        if isinstance(data, dict) and "client_id" in data:
+            return data
+        return None
+    except Exception as e:
+        logger.warning(f"Dynamic client registration failed for {server_url}: {e}")
+        return None

autogpt_platform/backend/backend/api/features/mcp/test_routes.py

@@ -0,0 +1,388 @@
+"""Tests for MCP API routes."""
+
+from unittest.mock import AsyncMock, patch
+
+import fastapi
+import fastapi.testclient
+from autogpt_libs.auth import get_user_id
+
+from backend.api.features.mcp.routes import router
+from backend.blocks.mcp.client import MCPClientError, MCPTool
+from backend.util.request import HTTPClientError
+
+app = fastapi.FastAPI()
+app.include_router(router)
+app.dependency_overrides[get_user_id] = lambda: "test-user-id"
+client = fastapi.testclient.TestClient(app)
+
+
+class TestDiscoverTools:
+    def test_discover_tools_success(self):
+        mock_tools = [
+            MCPTool(
+                name="get_weather",
+                description="Get weather for a city",
+                input_schema={
+                    "type": "object",
+                    "properties": {"city": {"type": "string"}},
+                    "required": ["city"],
+                },
+            ),
+            MCPTool(
+                name="add_numbers",
+                description="Add two numbers",
+                input_schema={
+                    "type": "object",
+                    "properties": {
+                        "a": {"type": "number"},
+                        "b": {"type": "number"},
+                    },
+                },
+            ),
+        ]
+
+        with (patch("backend.api.features.mcp.routes.MCPClient") as MockClient,):
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                return_value={
+                    "protocolVersion": "2025-03-26",
+                    "serverInfo": {"name": "test-server"},
+                }
+            )
+            instance.list_tools = AsyncMock(return_value=mock_tools)
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://mcp.example.com/mcp"},
+            )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert len(data["tools"]) == 2
+        assert data["tools"][0]["name"] == "get_weather"
+        assert data["tools"][1]["name"] == "add_numbers"
+        assert data["server_name"] == "test-server"
+        assert data["protocol_version"] == "2025-03-26"
+
+    def test_discover_tools_with_auth_token(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                return_value={"serverInfo": {}, "protocolVersion": "2025-03-26"}
+            )
+            instance.list_tools = AsyncMock(return_value=[])
+
+            response = client.post(
+                "/discover-tools",
+                json={
+                    "server_url": "https://mcp.example.com/mcp",
+                    "auth_token": "my-secret-token",
+                },
+            )
+
+        assert response.status_code == 200
+        MockClient.assert_called_once_with(
+            "https://mcp.example.com/mcp",
+            auth_token="my-secret-token",
+        )
+
+    def test_discover_tools_auto_uses_stored_credential(self):
+        """When no explicit token is given, stored MCP credentials are used."""
+        from pydantic import SecretStr
+
+        from backend.data.model import OAuth2Credentials
+
+        stored_cred = OAuth2Credentials(
+            provider="mcp",
+            title="MCP: example.com",
+            access_token=SecretStr("stored-token-123"),
+            refresh_token=None,
+            access_token_expires_at=None,
+            refresh_token_expires_at=None,
+            scopes=[],
+            metadata={"mcp_server_url": "https://mcp.example.com/mcp"},
+        )
+
+        with (
+            patch("backend.api.features.mcp.routes.MCPClient") as MockClient,
+            patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
+        ):
+            mock_cm.store.get_creds_by_provider = AsyncMock(return_value=[stored_cred])
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                return_value={"serverInfo": {}, "protocolVersion": "2025-03-26"}
+            )
+            instance.list_tools = AsyncMock(return_value=[])
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://mcp.example.com/mcp"},
+            )
+
+        assert response.status_code == 200
+        MockClient.assert_called_once_with(
+            "https://mcp.example.com/mcp",
+            auth_token="stored-token-123",
+        )
+
+    def test_discover_tools_mcp_error(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                side_effect=MCPClientError("Connection refused")
+            )
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://bad-server.example.com/mcp"},
+            )
+
+        assert response.status_code == 502
+        assert "Connection refused" in response.json()["detail"]
+
+    def test_discover_tools_generic_error(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(side_effect=Exception("Network timeout"))
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://timeout.example.com/mcp"},
+            )
+
+        assert response.status_code == 502
+        assert "Failed to connect" in response.json()["detail"]
+
+    def test_discover_tools_auth_required(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                side_effect=HTTPClientError("HTTP 401 Error: Unauthorized", 401)
+            )
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://auth-server.example.com/mcp"},
+            )
+
+        assert response.status_code == 401
+        assert "requires authentication" in response.json()["detail"]
+
+    def test_discover_tools_forbidden(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.initialize = AsyncMock(
+                side_effect=HTTPClientError("HTTP 403 Error: Forbidden", 403)
+            )
+
+            response = client.post(
+                "/discover-tools",
+                json={"server_url": "https://auth-server.example.com/mcp"},
+            )
+
+        assert response.status_code == 401
+        assert "requires authentication" in response.json()["detail"]
+
+    def test_discover_tools_missing_url(self):
+        response = client.post("/discover-tools", json={})
+        assert response.status_code == 422
+
+
+class TestOAuthLogin:
+    def test_oauth_login_success(self):
+        with (
+            patch("backend.api.features.mcp.routes.MCPClient") as MockClient,
+            patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
+            patch("backend.api.features.mcp.routes.settings") as mock_settings,
+            patch(
+                "backend.api.features.mcp.routes._register_mcp_client"
+            ) as mock_register,
+        ):
+            instance = MockClient.return_value
+            instance.discover_auth = AsyncMock(
+                return_value={
+                    "authorization_servers": ["https://auth.sentry.io"],
+                    "resource": "https://mcp.sentry.dev/mcp",
+                    "scopes_supported": ["openid"],
+                }
+            )
+            instance.discover_auth_server_metadata = AsyncMock(
+                return_value={
+                    "authorization_endpoint": "https://auth.sentry.io/authorize",
+                    "token_endpoint": "https://auth.sentry.io/token",
+                    "registration_endpoint": "https://auth.sentry.io/register",
+                }
+            )
+            mock_register.return_value = {
+                "client_id": "registered-client-id",
+                "client_secret": "registered-secret",
+            }
+            mock_cm.store.store_state_token = AsyncMock(
+                return_value=("state-token-123", "code-challenge-abc")
+            )
+            mock_settings.config.frontend_base_url = "http://localhost:3000"
+
+            response = client.post(
+                "/oauth/login",
+                json={"server_url": "https://mcp.sentry.dev/mcp"},
+            )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert "login_url" in data
+        assert data["state_token"] == "state-token-123"
+        assert "auth.sentry.io/authorize" in data["login_url"]
+        assert "registered-client-id" in data["login_url"]
+
+    def test_oauth_login_no_oauth_support(self):
+        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+            instance = MockClient.return_value
+            instance.discover_auth = AsyncMock(return_value=None)
+
+            response = client.post(
+                "/oauth/login",
+                json={"server_url": "https://simple-server.example.com/mcp"},
+            )
+
+        assert response.status_code == 400
+        assert "does not advertise OAuth" in response.json()["detail"]
+
+    def test_oauth_login_fallback_to_public_client(self):
+        """When DCR is unavailable, falls back to default public client ID."""
+        with (
+            patch("backend.api.features.mcp.routes.MCPClient") as MockClient,
+            patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
+            patch("backend.api.features.mcp.routes.settings") as mock_settings,
+        ):
+            instance = MockClient.return_value
+            instance.discover_auth = AsyncMock(
+                return_value={
+                    "authorization_servers": ["https://auth.example.com"],
+                    "resource": "https://mcp.example.com/mcp",
+                }
+            )
+            instance.discover_auth_server_metadata = AsyncMock(
+                return_value={
+                    "authorization_endpoint": "https://auth.example.com/authorize",
+                    "token_endpoint": "https://auth.example.com/token",
+                    # No registration_endpoint
+                }
+            )
+            mock_cm.store.store_state_token = AsyncMock(
+                return_value=("state-abc", "challenge-xyz")
+            )
+            mock_settings.config.frontend_base_url = "http://localhost:3000"
+
+            response = client.post(
+                "/oauth/login",
+                json={"server_url": "https://mcp.example.com/mcp"},
+            )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert "autogpt-platform" in data["login_url"]
+
+
+class TestOAuthCallback:
+    def test_oauth_callback_success(self):
+        from pydantic import SecretStr
+
+        from backend.data.model import OAuth2Credentials
+
+        mock_creds = OAuth2Credentials(
+            provider="mcp",
+            title=None,
+            access_token=SecretStr("access-token-xyz"),
+            refresh_token=None,
+            access_token_expires_at=None,
+            refresh_token_expires_at=None,
+            scopes=[],
+            metadata={
+                "mcp_token_url": "https://auth.sentry.io/token",
+                "mcp_resource_url": "https://mcp.sentry.dev/mcp",
+            },
+        )
+
+        with (
+            patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
+            patch("backend.api.features.mcp.routes.settings") as mock_settings,
+            patch("backend.api.features.mcp.routes.MCPOAuthHandler") as MockHandler,
+        ):
+            mock_settings.config.frontend_base_url = "http://localhost:3000"
+
+            # Mock state verification
+            mock_state = AsyncMock()
+            mock_state.state_metadata = {
+                "authorize_url": "https://auth.sentry.io/authorize",
+                "token_url": "https://auth.sentry.io/token",
+                "client_id": "test-client-id",
+                "client_secret": "test-secret",
+                "server_url": "https://mcp.sentry.dev/mcp",
+            }
+            mock_state.scopes = ["openid"]
+            mock_state.code_verifier = "verifier-123"
+            mock_cm.store.verify_state_token = AsyncMock(return_value=mock_state)
+            mock_cm.create = AsyncMock()
+
+            handler_instance = MockHandler.return_value
+            handler_instance.exchange_code_for_tokens = AsyncMock(
+                return_value=mock_creds
+            )
+
+            # Mock old credential cleanup
+            mock_cm.store.get_creds_by_provider = AsyncMock(return_value=[])
+
+            response = client.post(
+                "/oauth/callback",
+                json={"code": "auth-code-abc", "state_token": "state-token-123"},
+            )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert "id" in data
+        assert data["provider"] == "mcp"
+        assert data["type"] == "oauth2"
+        mock_cm.create.assert_called_once()
+
+    def test_oauth_callback_invalid_state(self):
+        with patch("backend.api.features.mcp.routes.creds_manager") as mock_cm:
+            mock_cm.store.verify_state_token = AsyncMock(return_value=None)
+
+            response = client.post(
+                "/oauth/callback",
+                json={"code": "auth-code", "state_token": "bad-state"},
+            )
+
+        assert response.status_code == 400
+        assert "Invalid or expired" in response.json()["detail"]
+
+    def test_oauth_callback_token_exchange_fails(self):
+        with (
+            patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
+            patch("backend.api.features.mcp.routes.settings") as mock_settings,
+            patch("backend.api.features.mcp.routes.MCPOAuthHandler") as MockHandler,
+        ):
+            mock_settings.config.frontend_base_url = "http://localhost:3000"
+            mock_state = AsyncMock()
+            mock_state.state_metadata = {
+                "authorize_url": "https://auth.example.com/authorize",
+                "token_url": "https://auth.example.com/token",
+                "client_id": "cid",
+                "server_url": "https://mcp.example.com/mcp",
+            }
+            mock_state.scopes = []
+            mock_state.code_verifier = "v"
+            mock_cm.store.verify_state_token = AsyncMock(return_value=mock_state)
+
+            handler_instance = MockHandler.return_value
+            handler_instance.exchange_code_for_tokens = AsyncMock(
+                side_effect=RuntimeError("Token exchange failed")
+            )
+
+            response = client.post(
+                "/oauth/callback",
+                json={"code": "bad-code", "state_token": "state"},
+            )
+
+        assert response.status_code == 400
+        assert "token exchange failed" in response.json()["detail"].lower()

autogpt_platform/backend/backend/api/rest_api.py

@@ -26,6 +26,7 @@ import backend.api.features.executions.review.routes
 import backend.api.features.library.db
 import backend.api.features.library.model
 import backend.api.features.library.routes
+import backend.api.features.mcp.routes as mcp_routes
 import backend.api.features.oauth
 import backend.api.features.otto.routes
 import backend.api.features.postmark.postmark
@@ -343,6 +344,11 @@ app.include_router(
     tags=["workspace"],
     prefix="/api/workspace",
 )
+app.include_router(
+    mcp_routes.router,
+    tags=["v2", "mcp"],
+    prefix="/api/mcp",
+)
 app.include_router(
     backend.api.features.oauth.router,
     tags=["oauth"],

autogpt_platform/backend/backend/blocks/mcp/block.py

@@ -0,0 +1,241 @@
+"""
+MCP (Model Context Protocol) Tool Block.
+
+A single dynamic block that can connect to any MCP server, discover available tools,
+and execute them. Works like AgentExecutorBlock — the user selects a tool from a
+dropdown and the input/output schema adapts dynamically.
+"""
+
+import json
+import logging
+from typing import Any, Literal
+
+from pydantic import SecretStr
+
+from backend.blocks.mcp.client import MCPClient, MCPClientError
+from backend.data.block import (
+    Block,
+    BlockCategory,
+    BlockInput,
+    BlockOutput,
+    BlockSchemaInput,
+    BlockSchemaOutput,
+    BlockType,
+)
+from backend.data.model import (
+    CredentialsField,
+    CredentialsMetaInput,
+    OAuth2Credentials,
+    SchemaField,
+)
+from backend.integrations.providers import ProviderName
+from backend.util.json import validate_with_jsonschema
+
+logger = logging.getLogger(__name__)
+
+TEST_CREDENTIALS = OAuth2Credentials(
+    id="test-mcp-cred",
+    provider="mcp",
+    access_token=SecretStr("mock-mcp-token"),
+    refresh_token=SecretStr("mock-refresh"),
+    scopes=[],
+    title="Mock MCP credential",
+)
+TEST_CREDENTIALS_INPUT = {
+    "provider": TEST_CREDENTIALS.provider,
+    "id": TEST_CREDENTIALS.id,
+    "type": TEST_CREDENTIALS.type,
+    "title": TEST_CREDENTIALS.title,
+}
+
+
+MCPCredentials = CredentialsMetaInput[Literal[ProviderName.MCP], Literal["oauth2"]]
+
+
+class MCPToolBlock(Block):
+    """
+    A block that connects to an MCP server, lets the user pick a tool,
+    and executes it with dynamic input/output schema.
+
+    The flow:
+    1. User provides an MCP server URL (and optional credentials)
+    2. Frontend calls the backend to get tool list from that URL
+    3. User selects a tool from a dropdown (available_tools)
+    4. The block's input schema updates to reflect the selected tool's parameters
+    5. On execution, the block calls the MCP server to run the tool
+    """
+
+    class Input(BlockSchemaInput):
+        server_url: str = SchemaField(
+            description="URL of the MCP server (Streamable HTTP endpoint)",
+            placeholder="https://mcp.example.com/mcp",
+        )
+        credentials: MCPCredentials = CredentialsField(
+            discriminator="server_url",
+            description="MCP server OAuth credentials",
+            default={},
+        )
+        selected_tool: str = SchemaField(
+            description="The MCP tool to execute",
+            placeholder="Select a tool",
+            default="",
+        )
+        tool_input_schema: dict[str, Any] = SchemaField(
+            description="JSON Schema for the selected tool's input parameters. "
+            "Populated automatically when a tool is selected.",
+            default={},
+            hidden=True,
+        )
+
+        tool_arguments: dict[str, Any] = SchemaField(
+            description="Arguments to pass to the selected MCP tool. "
+            "The fields here are defined by the tool's input schema.",
+            default={},
+        )
+
+        @classmethod
+        def get_input_schema(cls, data: BlockInput) -> dict[str, Any]:
+            """Return the tool's input schema so the builder UI renders dynamic fields."""
+            return data.get("tool_input_schema", {})
+
+        @classmethod
+        def get_input_defaults(cls, data: BlockInput) -> BlockInput:
+            """Return the current tool_arguments as defaults for the dynamic fields."""
+            return data.get("tool_arguments", {})
+
+        @classmethod
+        def get_missing_input(cls, data: BlockInput) -> set[str]:
+            """Check which required tool arguments are missing."""
+            required_fields = cls.get_input_schema(data).get("required", [])
+            tool_arguments = data.get("tool_arguments", {})
+            return set(required_fields) - set(tool_arguments)
+
+        @classmethod
+        def get_mismatch_error(cls, data: BlockInput) -> str | None:
+            """Validate tool_arguments against the tool's input schema."""
+            tool_schema = cls.get_input_schema(data)
+            if not tool_schema:
+                return None
+            tool_arguments = data.get("tool_arguments", {})
+            return validate_with_jsonschema(tool_schema, tool_arguments)
+
+    class Output(BlockSchemaOutput):
+        result: Any = SchemaField(description="The result returned by the MCP tool")
+        error: str = SchemaField(description="Error message if the tool call failed")
+
+    def __init__(self):
+        super().__init__(
+            id="a0a4b1c2-d3e4-4f56-a7b8-c9d0e1f2a3b4",
+            description="Connect to any MCP server and execute its tools. "
+            "Provide a server URL, select a tool, and pass arguments dynamically.",
+            categories={BlockCategory.DEVELOPER_TOOLS},
+            input_schema=MCPToolBlock.Input,
+            output_schema=MCPToolBlock.Output,
+            block_type=BlockType.STANDARD,
+            test_credentials=TEST_CREDENTIALS,
+            test_input={
+                "server_url": "https://mcp.example.com/mcp",
+                "credentials": TEST_CREDENTIALS_INPUT,
+                "selected_tool": "get_weather",
+                "tool_input_schema": {
+                    "type": "object",
+                    "properties": {"city": {"type": "string"}},
+                    "required": ["city"],
+                },
+                "tool_arguments": {"city": "London"},
+            },
+            test_output=[
+                (
+                    "result",
+                    {"weather": "sunny", "temperature": 20},
+                ),
+            ],
+            test_mock={
+                "_call_mcp_tool": lambda *a, **kw: {
+                    "weather": "sunny",
+                    "temperature": 20,
+                },
+            },
+        )
+
+    async def _call_mcp_tool(
+        self,
+        server_url: str,
+        tool_name: str,
+        arguments: dict[str, Any],
+        auth_token: str | None = None,
+    ) -> Any:
+        """Call a tool on the MCP server. Extracted for easy mocking in tests."""
+        client = MCPClient(server_url, auth_token=auth_token)
+        await client.initialize()
+        result = await client.call_tool(tool_name, arguments)
+
+        if result.is_error:
+            error_text = ""
+            for item in result.content:
+                if item.get("type") == "text":
+                    error_text += item.get("text", "")
+            raise MCPClientError(
+                f"MCP tool '{tool_name}' returned an error: "
+                f"{error_text or 'Unknown error'}"
+            )
+
+        # Extract text content from the result
+        output_parts = []
+        for item in result.content:
+            if item.get("type") == "text":
+                text = item.get("text", "")
+                # Try to parse as JSON for structured output
+                try:
+                    output_parts.append(json.loads(text))
+                except (json.JSONDecodeError, ValueError):
+                    output_parts.append(text)
+            elif item.get("type") == "image":
+                output_parts.append(
+                    {
+                        "type": "image",
+                        "data": item.get("data"),
+                        "mimeType": item.get("mimeType"),
+                    }
+                )
+            elif item.get("type") == "resource":
+                output_parts.append(item.get("resource", {}))
+
+        # If single result, unwrap
+        if len(output_parts) == 1:
+            return output_parts[0]
+        return output_parts if output_parts else None
+
+    async def run(
+        self,
+        input_data: Input,
+        *,
+        user_id: str,
+        credentials: OAuth2Credentials | None = None,
+        **kwargs,
+    ) -> BlockOutput:
+        if not input_data.server_url:
+            yield "error", "MCP server URL is required"
+            return
+
+        if not input_data.selected_tool:
+            yield "error", "No tool selected. Please select a tool from the dropdown."
+            return
+
+        auth_token = (
+            credentials.access_token.get_secret_value() if credentials else None
+        )
+
+        try:
+            result = await self._call_mcp_tool(
+                server_url=input_data.server_url,
+                tool_name=input_data.selected_tool,
+                arguments=input_data.tool_arguments,
+                auth_token=auth_token,
+            )
+            yield "result", result
+        except MCPClientError as e:
+            yield "error", str(e)
+        except Exception as e:
+            logger.exception(f"MCP tool call failed: {e}")
+            yield "error", f"MCP tool call failed: {str(e)}"

autogpt_platform/backend/backend/blocks/mcp/client.py

@@ -0,0 +1,318 @@
+"""
+MCP (Model Context Protocol) HTTP client.
+
+Implements the MCP Streamable HTTP transport for listing tools and calling tools
+on remote MCP servers. Uses JSON-RPC 2.0 over HTTP POST.
+
+Handles both JSON and SSE (text/event-stream) response formats per the MCP spec.
+
+Reference: https://modelcontextprotocol.io/specification/2025-03-26/basic/transports
+"""
+
+import json
+import logging
+from dataclasses import dataclass, field
+from typing import Any
+
+from backend.util.request import Requests
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class MCPTool:
+    """Represents an MCP tool discovered from a server."""
+
+    name: str
+    description: str
+    input_schema: dict[str, Any]
+
+
+@dataclass
+class MCPCallResult:
+    """Result from calling an MCP tool."""
+
+    content: list[dict[str, Any]] = field(default_factory=list)
+    is_error: bool = False
+
+
+class MCPClientError(Exception):
+    """Raised when an MCP protocol error occurs."""
+
+    pass
+
+
+class MCPClient:
+    """
+    Async HTTP client for the MCP Streamable HTTP transport.
+
+    Communicates with MCP servers using JSON-RPC 2.0 over HTTP POST.
+    Supports optional Bearer token authentication.
+    """
+
+    def __init__(
+        self,
+        server_url: str,
+        auth_token: str | None = None,
+    ):
+        self.server_url = server_url.rstrip("/")
+        self.auth_token = auth_token
+        self._request_id = 0
+        self._session_id: str | None = None
+
+    def _next_id(self) -> int:
+        self._request_id += 1
+        return self._request_id
+
+    def _build_headers(self) -> dict[str, str]:
+        headers = {
+            "Content-Type": "application/json",
+            "Accept": "application/json, text/event-stream",
+        }
+        if self.auth_token:
+            headers["Authorization"] = f"Bearer {self.auth_token}"
+        if self._session_id:
+            headers["Mcp-Session-Id"] = self._session_id
+        return headers
+
+    def _build_jsonrpc_request(
+        self, method: str, params: dict[str, Any] | None = None
+    ) -> dict[str, Any]:
+        req: dict[str, Any] = {
+            "jsonrpc": "2.0",
+            "method": method,
+            "id": self._next_id(),
+        }
+        if params is not None:
+            req["params"] = params
+        return req
+
+    @staticmethod
+    def _parse_sse_response(text: str) -> dict[str, Any]:
+        """Parse an SSE (text/event-stream) response body into JSON-RPC data.
+
+        MCP servers may return responses as SSE with format:
+            event: message
+            data: {"jsonrpc":"2.0","result":{...},"id":1}
+
+        We extract the last `data:` line that contains a JSON-RPC response
+        (i.e. has an "id" field), which is the reply to our request.
+        """
+        last_data: dict[str, Any] | None = None
+        for line in text.splitlines():
+            stripped = line.strip()
+            if stripped.startswith("data:"):
+                payload = stripped[len("data:") :].strip()
+                if not payload:
+                    continue
+                try:
+                    parsed = json.loads(payload)
+                    # Only keep JSON-RPC responses (have "id"), skip notifications
+                    if isinstance(parsed, dict) and "id" in parsed:
+                        last_data = parsed
+                except (json.JSONDecodeError, ValueError):
+                    continue
+        if last_data is None:
+            raise MCPClientError("No JSON-RPC response found in SSE stream")
+        return last_data
+
+    async def _send_request(
+        self, method: str, params: dict[str, Any] | None = None
+    ) -> Any:
+        """Send a JSON-RPC request to the MCP server and return the result.
+
+        Handles both ``application/json`` and ``text/event-stream`` responses
+        as required by the MCP Streamable HTTP transport specification.
+        """
+        payload = self._build_jsonrpc_request(method, params)
+        headers = self._build_headers()
+
+        requests = Requests(
+            raise_for_status=True,
+            extra_headers=headers,
+        )
+        response = await requests.post(self.server_url, json=payload)
+
+        # Capture session ID from response (MCP Streamable HTTP transport)
+        session_id = response.headers.get("Mcp-Session-Id")
+        if session_id:
+            self._session_id = session_id
+
+        content_type = response.headers.get("content-type", "")
+        if "text/event-stream" in content_type:
+            body = self._parse_sse_response(response.text())
+        else:
+            try:
+                body = response.json()
+            except Exception as e:
+                raise MCPClientError(
+                    f"MCP server returned non-JSON response: {e}"
+                ) from e
+
+        # Handle JSON-RPC error
+        if "error" in body:
+            error = body["error"]
+            if isinstance(error, dict):
+                raise MCPClientError(
+                    f"MCP server error [{error.get('code', '?')}]: "
+                    f"{error.get('message', 'Unknown error')}"
+                )
+            raise MCPClientError(f"MCP server error: {error}")
+
+        return body.get("result")
+
+    async def _send_notification(self, method: str) -> None:
+        """Send a JSON-RPC notification (no id, no response expected)."""
+        headers = self._build_headers()
+        notification = {"jsonrpc": "2.0", "method": method}
+        requests = Requests(
+            raise_for_status=False,
+            extra_headers=headers,
+        )
+        await requests.post(self.server_url, json=notification)
+
+    async def discover_auth(self) -> dict[str, Any] | None:
+        """Probe the MCP server's OAuth metadata (RFC 9728 / MCP spec).
+
+        Returns ``None`` if the server doesn't require auth, otherwise returns
+        a dict with:
+          - ``authorization_servers``: list of authorization server URLs
+          - ``resource``: the resource indicator URL (usually the MCP endpoint)
+          - ``scopes_supported``: optional list of supported scopes
+
+        The caller can then fetch the authorization server metadata to get
+        ``authorization_endpoint``, ``token_endpoint``, etc.
+        """
+        from urllib.parse import urlparse
+
+        parsed = urlparse(self.server_url)
+        base = f"{parsed.scheme}://{parsed.netloc}"
+
+        # Build candidates for protected-resource metadata (per RFC 9728)
+        path = parsed.path.rstrip("/")
+        candidates = []
+        if path and path != "/":
+            candidates.append(f"{base}/.well-known/oauth-protected-resource{path}")
+        candidates.append(f"{base}/.well-known/oauth-protected-resource")
+
+        requests = Requests(
+            raise_for_status=False,
+        )
+        for url in candidates:
+            try:
+                resp = await requests.get(url)
+                if resp.status == 200:
+                    data = resp.json()
+                    if isinstance(data, dict) and "authorization_servers" in data:
+                        return data
+            except Exception:
+                continue
+
+        return None
+
+    async def discover_auth_server_metadata(
+        self, auth_server_url: str
+    ) -> dict[str, Any] | None:
+        """Fetch the OAuth Authorization Server Metadata (RFC 8414).
+
+        Given an authorization server URL, returns a dict with:
+          - ``authorization_endpoint``
+          - ``token_endpoint``
+          - ``registration_endpoint`` (for dynamic client registration)
+          - ``scopes_supported``
+          - ``code_challenge_methods_supported``
+          - etc.
+        """
+        from urllib.parse import urlparse
+
+        parsed = urlparse(auth_server_url)
+        base = f"{parsed.scheme}://{parsed.netloc}"
+        path = parsed.path.rstrip("/")
+
+        # Try standard metadata endpoints (RFC 8414 and OpenID Connect)
+        candidates = []
+        if path and path != "/":
+            candidates.append(f"{base}/.well-known/oauth-authorization-server{path}")
+        candidates.append(f"{base}/.well-known/oauth-authorization-server")
+        candidates.append(f"{base}/.well-known/openid-configuration")
+
+        requests = Requests(
+            raise_for_status=False,
+        )
+        for url in candidates:
+            try:
+                resp = await requests.get(url)
+                if resp.status == 200:
+                    data = resp.json()
+                    if isinstance(data, dict) and "authorization_endpoint" in data:
+                        return data
+            except Exception:
+                continue
+
+        return None
+
+    async def initialize(self) -> dict[str, Any]:
+        """
+        Send the MCP initialize request.
+
+        This is required by the MCP protocol before any other requests.
+        Returns the server's capabilities.
+        """
+        result = await self._send_request(
+            "initialize",
+            {
+                "protocolVersion": "2025-03-26",
+                "capabilities": {},
+                "clientInfo": {"name": "AutoGPT-Platform", "version": "1.0.0"},
+            },
+        )
+        # Send initialized notification (no response expected)
+        await self._send_notification("notifications/initialized")
+
+        return result or {}
+
+    async def list_tools(self) -> list[MCPTool]:
+        """
+        Discover available tools from the MCP server.
+
+        Returns a list of MCPTool objects with name, description, and input schema.
+        """
+        result = await self._send_request("tools/list")
+        if not result or "tools" not in result:
+            return []
+
+        tools = []
+        for tool_data in result["tools"]:
+            tools.append(
+                MCPTool(
+                    name=tool_data.get("name", ""),
+                    description=tool_data.get("description", ""),
+                    input_schema=tool_data.get("inputSchema", {}),
+                )
+            )
+        return tools
+
+    async def call_tool(
+        self, tool_name: str, arguments: dict[str, Any]
+    ) -> MCPCallResult:
+        """
+        Call a tool on the MCP server.
+
+        Args:
+            tool_name: The name of the tool to call.
+            arguments: The arguments to pass to the tool.
+
+        Returns:
+            MCPCallResult with the tool's response content.
+        """
+        result = await self._send_request(
+            "tools/call",
+            {"name": tool_name, "arguments": arguments},
+        )
+        if not result:
+            return MCPCallResult(is_error=True)
+
+        return MCPCallResult(
+            content=result.get("content", []),
+            is_error=result.get("isError", False),
+        )

autogpt_platform/backend/backend/blocks/mcp/conftest.py

@@ -0,0 +1,42 @@
+"""
+Conftest for MCP block tests.
+
+Override the session-scoped server and graph_cleanup fixtures from
+backend/conftest.py so that MCP integration tests don't spin up the
+full SpinTestServer infrastructure.
+"""
+
+import pytest
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    config.addinivalue_line("markers", "e2e: end-to-end tests requiring network")
+
+
+def pytest_collection_modifyitems(
+    config: pytest.Config, items: list[pytest.Item]
+) -> None:
+    """Skip e2e tests unless --run-e2e is passed."""
+    if not config.getoption("--run-e2e", default=False):
+        skip_e2e = pytest.mark.skip(reason="need --run-e2e option to run")
+        for item in items:
+            if "e2e" in item.keywords:
+                item.add_marker(skip_e2e)
+
+
+def pytest_addoption(parser: pytest.Parser) -> None:
+    parser.addoption(
+        "--run-e2e", action="store_true", default=False, help="run e2e tests"
+    )
+
+
+@pytest.fixture(scope="session")
+def server():
+    """No-op override — MCP tests don't need the full platform server."""
+    yield None
+
+
+@pytest.fixture(scope="session", autouse=True)
+def graph_cleanup(server):
+    """No-op override — MCP tests don't create graphs."""
+    yield

autogpt_platform/backend/backend/blocks/mcp/oauth.py

@@ -0,0 +1,198 @@
+"""
+MCP OAuth handler for MCP servers that use OAuth 2.1 authorization.
+
+Unlike other OAuth handlers (GitHub, Google, etc.) where endpoints are fixed,
+MCP servers have dynamic endpoints discovered via RFC 9728 / RFC 8414 metadata.
+This handler accepts those endpoints at construction time.
+"""
+
+import logging
+import time
+import urllib.parse
+from typing import ClassVar, Optional
+
+from pydantic import SecretStr
+
+from backend.data.model import OAuth2Credentials
+from backend.integrations.oauth.base import BaseOAuthHandler
+from backend.integrations.providers import ProviderName
+from backend.util.request import Requests
+
+logger = logging.getLogger(__name__)
+
+
+class MCPOAuthHandler(BaseOAuthHandler):
+    """
+    OAuth handler for MCP servers with dynamically-discovered endpoints.
+
+    Construction requires the authorization and token endpoint URLs,
+    which are obtained via MCP OAuth metadata discovery
+    (``MCPClient.discover_auth`` + ``discover_auth_server_metadata``).
+    """
+
+    PROVIDER_NAME: ClassVar[ProviderName | str] = ProviderName.MCP
+    DEFAULT_SCOPES: ClassVar[list[str]] = []
+
+    def __init__(
+        self,
+        client_id: str,
+        client_secret: str,
+        redirect_uri: str,
+        *,
+        authorize_url: str,
+        token_url: str,
+        revoke_url: str | None = None,
+        resource_url: str | None = None,
+    ):
+        self.client_id = client_id
+        self.client_secret = client_secret
+        self.redirect_uri = redirect_uri
+        self.authorize_url = authorize_url
+        self.token_url = token_url
+        self.revoke_url = revoke_url
+        self.resource_url = resource_url
+
+    def get_login_url(
+        self,
+        scopes: list[str],
+        state: str,
+        code_challenge: Optional[str],
+    ) -> str:
+        scopes = self.handle_default_scopes(scopes)
+
+        params: dict[str, str] = {
+            "response_type": "code",
+            "client_id": self.client_id,
+            "redirect_uri": self.redirect_uri,
+            "state": state,
+        }
+        if scopes:
+            params["scope"] = " ".join(scopes)
+        # PKCE (S256) — included when the caller provides a code_challenge
+        if code_challenge:
+            params["code_challenge"] = code_challenge
+            params["code_challenge_method"] = "S256"
+        # MCP spec requires resource indicator (RFC 8707)
+        if self.resource_url:
+            params["resource"] = self.resource_url
+
+        return f"{self.authorize_url}?{urllib.parse.urlencode(params)}"
+
+    async def exchange_code_for_tokens(
+        self,
+        code: str,
+        scopes: list[str],
+        code_verifier: Optional[str],
+    ) -> OAuth2Credentials:
+        data: dict[str, str] = {
+            "grant_type": "authorization_code",
+            "code": code,
+            "redirect_uri": self.redirect_uri,
+            "client_id": self.client_id,
+        }
+        if self.client_secret:
+            data["client_secret"] = self.client_secret
+        if code_verifier:
+            data["code_verifier"] = code_verifier
+        if self.resource_url:
+            data["resource"] = self.resource_url
+
+        response = await Requests(raise_for_status=True).post(
+            self.token_url,
+            data=data,
+            headers={"Content-Type": "application/x-www-form-urlencoded"},
+        )
+        tokens = response.json()
+
+        if "error" in tokens:
+            raise RuntimeError(
+                f"Token exchange failed: {tokens.get('error_description', tokens['error'])}"
+            )
+
+        now = int(time.time())
+        expires_in = tokens.get("expires_in")
+
+        return OAuth2Credentials(
+            provider=str(self.PROVIDER_NAME),
+            title=None,
+            access_token=SecretStr(tokens["access_token"]),
+            refresh_token=(
+                SecretStr(tokens["refresh_token"])
+                if tokens.get("refresh_token")
+                else None
+            ),
+            access_token_expires_at=now + expires_in if expires_in else None,
+            refresh_token_expires_at=None,
+            scopes=scopes,
+            metadata={
+                "mcp_token_url": self.token_url,
+                "mcp_resource_url": self.resource_url,
+            },
+        )
+
+    async def _refresh_tokens(
+        self, credentials: OAuth2Credentials
+    ) -> OAuth2Credentials:
+        if not credentials.refresh_token:
+            raise ValueError("No refresh token available for MCP OAuth credentials")
+
+        data: dict[str, str] = {
+            "grant_type": "refresh_token",
+            "refresh_token": credentials.refresh_token.get_secret_value(),
+            "client_id": self.client_id,
+        }
+        if self.client_secret:
+            data["client_secret"] = self.client_secret
+        if self.resource_url:
+            data["resource"] = self.resource_url
+
+        response = await Requests(raise_for_status=True).post(
+            self.token_url,
+            data=data,
+            headers={"Content-Type": "application/x-www-form-urlencoded"},
+        )
+        tokens = response.json()
+
+        if "error" in tokens:
+            raise RuntimeError(
+                f"Token refresh failed: {tokens.get('error_description', tokens['error'])}"
+            )
+
+        now = int(time.time())
+        expires_in = tokens.get("expires_in")
+
+        return OAuth2Credentials(
+            id=credentials.id,
+            provider=str(self.PROVIDER_NAME),
+            title=credentials.title,
+            access_token=SecretStr(tokens["access_token"]),
+            refresh_token=(
+                SecretStr(tokens["refresh_token"])
+                if tokens.get("refresh_token")
+                else credentials.refresh_token
+            ),
+            access_token_expires_at=now + expires_in if expires_in else None,
+            refresh_token_expires_at=credentials.refresh_token_expires_at,
+            scopes=credentials.scopes,
+            metadata=credentials.metadata,
+        )
+
+    async def revoke_tokens(self, credentials: OAuth2Credentials) -> bool:
+        if not self.revoke_url:
+            return False
+
+        try:
+            data = {
+                "token": credentials.access_token.get_secret_value(),
+                "token_type_hint": "access_token",
+                "client_id": self.client_id,
+            }
+            await Requests().post(
+                self.revoke_url,
+                data=data,
+                headers={"Content-Type": "application/x-www-form-urlencoded"},
+            )
+            return True
+        except Exception:
+            logger.warning("Failed to revoke MCP OAuth tokens", exc_info=True)
+            return False

autogpt_platform/backend/backend/blocks/mcp/test_e2e.py

@@ -0,0 +1,104 @@
+"""
+End-to-end tests against a real public MCP server.
+
+These tests hit the OpenAI docs MCP server (https://developers.openai.com/mcp)
+which is publicly accessible without authentication and returns SSE responses.
+
+Mark: These are tagged with ``@pytest.mark.e2e`` so they can be run/skipped
+independently of the rest of the test suite (they require network access).
+"""
+
+import json
+
+import pytest
+
+from backend.blocks.mcp.client import MCPClient
+
+# Public MCP server that requires no authentication
+OPENAI_DOCS_MCP_URL = "https://developers.openai.com/mcp"
+
+
+@pytest.mark.e2e
+class TestRealMCPServer:
+    """Tests against the live OpenAI docs MCP server."""
+
+    @pytest.mark.asyncio
+    async def test_initialize(self):
+        """Verify we can complete the MCP handshake with a real server."""
+        client = MCPClient(OPENAI_DOCS_MCP_URL)
+        result = await client.initialize()
+
+        assert result["protocolVersion"] == "2025-03-26"
+        assert "serverInfo" in result
+        assert result["serverInfo"]["name"] == "openai-docs-mcp"
+        assert "tools" in result.get("capabilities", {})
+
+    @pytest.mark.asyncio
+    async def test_list_tools(self):
+        """Verify we can discover tools from a real MCP server."""
+        client = MCPClient(OPENAI_DOCS_MCP_URL)
+        await client.initialize()
+        tools = await client.list_tools()
+
+        assert len(tools) >= 3  # server has at least 5 tools as of writing
+
+        tool_names = {t.name for t in tools}
+        # These tools are documented and should be stable
+        assert "search_openai_docs" in tool_names
+        assert "list_openai_docs" in tool_names
+        assert "fetch_openai_doc" in tool_names
+
+        # Verify schema structure
+        search_tool = next(t for t in tools if t.name == "search_openai_docs")
+        assert "query" in search_tool.input_schema.get("properties", {})
+        assert "query" in search_tool.input_schema.get("required", [])
+
+    @pytest.mark.asyncio
+    async def test_call_tool_list_api_endpoints(self):
+        """Call the list_api_endpoints tool and verify we get real data."""
+        client = MCPClient(OPENAI_DOCS_MCP_URL)
+        await client.initialize()
+        result = await client.call_tool("list_api_endpoints", {})
+
+        assert not result.is_error
+        assert len(result.content) >= 1
+        assert result.content[0]["type"] == "text"
+
+        data = json.loads(result.content[0]["text"])
+        assert "paths" in data or "urls" in data
+        # The OpenAI API should have many endpoints
+        total = data.get("total", len(data.get("paths", [])))
+        assert total > 50
+
+    @pytest.mark.asyncio
+    async def test_call_tool_search(self):
+        """Search for docs and verify we get results."""
+        client = MCPClient(OPENAI_DOCS_MCP_URL)
+        await client.initialize()
+        result = await client.call_tool(
+            "search_openai_docs", {"query": "chat completions", "limit": 3}
+        )
+
+        assert not result.is_error
+        assert len(result.content) >= 1
+
+    @pytest.mark.asyncio
+    async def test_sse_response_handling(self):
+        """Verify the client correctly handles SSE responses from a real server.
+
+        This is the key test — our local test server returns JSON,
+        but real MCP servers typically return SSE. This proves the
+        SSE parsing works end-to-end.
+        """
+        client = MCPClient(OPENAI_DOCS_MCP_URL)
+        # initialize() internally calls _send_request which must parse SSE
+        result = await client.initialize()
+
+        # If we got here without error, SSE parsing works
+        assert isinstance(result, dict)
+        assert "protocolVersion" in result
+
+        # Also verify list_tools works (another SSE response)
+        tools = await client.list_tools()
+        assert len(tools) > 0
+        assert all(hasattr(t, "name") for t in tools)

autogpt_platform/backend/backend/blocks/mcp/test_integration.py

@@ -0,0 +1,389 @@
+"""
+Integration tests for MCP client and MCPToolBlock against a real HTTP server.
+
+These tests spin up a local MCP test server and run the full client/block flow
+against it — no mocking, real HTTP requests.
+"""
+
+import asyncio
+import json
+import threading
+from unittest.mock import patch
+
+import pytest
+from aiohttp import web
+from pydantic import SecretStr
+
+from backend.blocks.mcp.block import MCPToolBlock
+from backend.blocks.mcp.client import MCPClient
+from backend.blocks.mcp.test_server import create_test_mcp_app
+from backend.data.model import OAuth2Credentials
+
+MOCK_USER_ID = "test-user-integration"
+
+
+class _MCPTestServer:
+    """
+    Run an MCP test server in a background thread with its own event loop.
+    This avoids event loop conflicts with pytest-asyncio.
+    """
+
+    def __init__(self, auth_token: str | None = None):
+        self.auth_token = auth_token
+        self.url: str = ""
+        self._runner: web.AppRunner | None = None
+        self._loop: asyncio.AbstractEventLoop | None = None
+        self._thread: threading.Thread | None = None
+        self._started = threading.Event()
+
+    def _run(self):
+        self._loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self._loop)
+        self._loop.run_until_complete(self._start())
+        self._started.set()
+        self._loop.run_forever()
+
+    async def _start(self):
+        app = create_test_mcp_app(auth_token=self.auth_token)
+        self._runner = web.AppRunner(app)
+        await self._runner.setup()
+        site = web.TCPSite(self._runner, "127.0.0.1", 0)
+        await site.start()
+        port = site._server.sockets[0].getsockname()[1]  # type: ignore[union-attr]
+        self.url = f"http://127.0.0.1:{port}/mcp"
+
+    def start(self):
+        self._thread = threading.Thread(target=self._run, daemon=True)
+        self._thread.start()
+        if not self._started.wait(timeout=5):
+            raise RuntimeError("MCP test server failed to start within 5 seconds")
+        return self
+
+    def stop(self):
+        if self._loop and self._runner:
+            asyncio.run_coroutine_threadsafe(self._runner.cleanup(), self._loop).result(
+                timeout=5
+            )
+            self._loop.call_soon_threadsafe(self._loop.stop)
+        if self._thread:
+            self._thread.join(timeout=5)
+
+
+@pytest.fixture(scope="module")
+def mcp_server():
+    """Start a local MCP test server in a background thread."""
+    server = _MCPTestServer()
+    server.start()
+    yield server.url
+    server.stop()
+
+
+@pytest.fixture(scope="module")
+def mcp_server_with_auth():
+    """Start a local MCP test server with auth in a background thread."""
+    server = _MCPTestServer(auth_token="test-secret-token")
+    server.start()
+    yield server.url, "test-secret-token"
+    server.stop()
+
+
+@pytest.fixture(autouse=True)
+def _allow_localhost():
+    """
+    Allow 127.0.0.1 through SSRF protection for integration tests.
+
+    The Requests class blocks private IPs by default. We patch the Requests
+    constructor to always include 127.0.0.1 as a trusted origin so the local
+    test server is reachable.
+    """
+    from backend.util.request import Requests
+
+    original_init = Requests.__init__
+
+    def patched_init(self, *args, **kwargs):
+        trusted = list(kwargs.get("trusted_origins") or [])
+        trusted.append("http://127.0.0.1")
+        kwargs["trusted_origins"] = trusted
+        original_init(self, *args, **kwargs)
+
+    with patch.object(Requests, "__init__", patched_init):
+        yield
+
+
+def _make_client(url: str, auth_token: str | None = None) -> MCPClient:
+    """Create an MCPClient for integration tests."""
+    return MCPClient(url, auth_token=auth_token)
+
+
+# ── MCPClient integration tests ──────────────────────────────────────
+
+
+class TestMCPClientIntegration:
+    """Test MCPClient against a real local MCP server."""
+
+    @pytest.mark.asyncio
+    async def test_initialize(self, mcp_server):
+        client = _make_client(mcp_server)
+        result = await client.initialize()
+
+        assert result["protocolVersion"] == "2025-03-26"
+        assert result["serverInfo"]["name"] == "test-mcp-server"
+        assert "tools" in result["capabilities"]
+
+    @pytest.mark.asyncio
+    async def test_list_tools(self, mcp_server):
+        client = _make_client(mcp_server)
+        await client.initialize()
+        tools = await client.list_tools()
+
+        assert len(tools) == 3
+
+        tool_names = {t.name for t in tools}
+        assert tool_names == {"get_weather", "add_numbers", "echo"}
+
+        # Check get_weather schema
+        weather = next(t for t in tools if t.name == "get_weather")
+        assert weather.description == "Get current weather for a city"
+        assert "city" in weather.input_schema["properties"]
+        assert weather.input_schema["required"] == ["city"]
+
+        # Check add_numbers schema
+        add = next(t for t in tools if t.name == "add_numbers")
+        assert "a" in add.input_schema["properties"]
+        assert "b" in add.input_schema["properties"]
+
+    @pytest.mark.asyncio
+    async def test_call_tool_get_weather(self, mcp_server):
+        client = _make_client(mcp_server)
+        await client.initialize()
+        result = await client.call_tool("get_weather", {"city": "London"})
+
+        assert not result.is_error
+        assert len(result.content) == 1
+        assert result.content[0]["type"] == "text"
+
+        data = json.loads(result.content[0]["text"])
+        assert data["city"] == "London"
+        assert data["temperature"] == 22
+        assert data["condition"] == "sunny"
+
+    @pytest.mark.asyncio
+    async def test_call_tool_add_numbers(self, mcp_server):
+        client = _make_client(mcp_server)
+        await client.initialize()
+        result = await client.call_tool("add_numbers", {"a": 3, "b": 7})
+
+        assert not result.is_error
+        data = json.loads(result.content[0]["text"])
+        assert data["result"] == 10
+
+    @pytest.mark.asyncio
+    async def test_call_tool_echo(self, mcp_server):
+        client = _make_client(mcp_server)
+        await client.initialize()
+        result = await client.call_tool("echo", {"message": "Hello MCP!"})
+
+        assert not result.is_error
+        assert result.content[0]["text"] == "Hello MCP!"
+
+    @pytest.mark.asyncio
+    async def test_call_unknown_tool(self, mcp_server):
+        client = _make_client(mcp_server)
+        await client.initialize()
+        result = await client.call_tool("nonexistent_tool", {})
+
+        assert result.is_error
+        assert "Unknown tool" in result.content[0]["text"]
+
+    @pytest.mark.asyncio
+    async def test_auth_success(self, mcp_server_with_auth):
+        url, token = mcp_server_with_auth
+        client = _make_client(url, auth_token=token)
+        result = await client.initialize()
+
+        assert result["protocolVersion"] == "2025-03-26"
+
+        tools = await client.list_tools()
+        assert len(tools) == 3
+
+    @pytest.mark.asyncio
+    async def test_auth_failure(self, mcp_server_with_auth):
+        url, _ = mcp_server_with_auth
+        client = _make_client(url, auth_token="wrong-token")
+
+        with pytest.raises(Exception):
+            await client.initialize()
+
+    @pytest.mark.asyncio
+    async def test_auth_missing(self, mcp_server_with_auth):
+        url, _ = mcp_server_with_auth
+        client = _make_client(url)
+
+        with pytest.raises(Exception):
+            await client.initialize()
+
+
+# ── MCPToolBlock integration tests ───────────────────────────────────
+
+
+class TestMCPToolBlockIntegration:
+    """Test MCPToolBlock end-to-end against a real local MCP server."""
+
+    @pytest.mark.asyncio
+    async def test_full_flow_get_weather(self, mcp_server):
+        """Full flow: discover tools, select one, execute it."""
+        # Step 1: Discover tools (simulating what the frontend/API would do)
+        client = _make_client(mcp_server)
+        await client.initialize()
+        tools = await client.list_tools()
+        assert len(tools) == 3
+
+        # Step 2: User selects "get_weather" and we get its schema
+        weather_tool = next(t for t in tools if t.name == "get_weather")
+
+        # Step 3: Execute the block — no credentials (public server)
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=mcp_server,
+            selected_tool="get_weather",
+            tool_input_schema=weather_tool.input_schema,
+            tool_arguments={"city": "Paris"},
+        )
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        result = outputs[0][1]
+        assert result["city"] == "Paris"
+        assert result["temperature"] == 22
+        assert result["condition"] == "sunny"
+
+    @pytest.mark.asyncio
+    async def test_full_flow_add_numbers(self, mcp_server):
+        """Full flow for add_numbers tool."""
+        client = _make_client(mcp_server)
+        await client.initialize()
+        tools = await client.list_tools()
+        add_tool = next(t for t in tools if t.name == "add_numbers")
+
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=mcp_server,
+            selected_tool="add_numbers",
+            tool_input_schema=add_tool.input_schema,
+            tool_arguments={"a": 42, "b": 58},
+        )
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        assert outputs[0][1]["result"] == 100
+
+    @pytest.mark.asyncio
+    async def test_full_flow_echo_plain_text(self, mcp_server):
+        """Verify plain text (non-JSON) responses work."""
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=mcp_server,
+            selected_tool="echo",
+            tool_input_schema={
+                "type": "object",
+                "properties": {"message": {"type": "string"}},
+                "required": ["message"],
+            },
+            tool_arguments={"message": "Hello from AutoGPT!"},
+        )
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        assert outputs[0][1] == "Hello from AutoGPT!"
+
+    @pytest.mark.asyncio
+    async def test_full_flow_unknown_tool_yields_error(self, mcp_server):
+        """Calling an unknown tool should yield an error output."""
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=mcp_server,
+            selected_tool="nonexistent_tool",
+            tool_arguments={},
+        )
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "error"
+        assert "returned an error" in outputs[0][1]
+
+    @pytest.mark.asyncio
+    async def test_full_flow_with_auth(self, mcp_server_with_auth):
+        """Full flow with authentication via credentials kwarg."""
+        url, token = mcp_server_with_auth
+
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=url,
+            selected_tool="echo",
+            tool_input_schema={
+                "type": "object",
+                "properties": {"message": {"type": "string"}},
+                "required": ["message"],
+            },
+            tool_arguments={"message": "Authenticated!"},
+        )
+
+        # Pass credentials via the standard kwarg (as the executor would)
+        test_creds = OAuth2Credentials(
+            id="test-cred",
+            provider="mcp",
+            access_token=SecretStr(token),
+            refresh_token=SecretStr(""),
+            scopes=[],
+            title="Test MCP credential",
+        )
+
+        outputs = []
+        async for name, data in block.run(
+            input_data, user_id=MOCK_USER_ID, credentials=test_creds
+        ):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        assert outputs[0][1] == "Authenticated!"
+
+    @pytest.mark.asyncio
+    async def test_no_credentials_runs_without_auth(self, mcp_server):
+        """Block runs without auth when no credentials are provided."""
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url=mcp_server,
+            selected_tool="echo",
+            tool_input_schema={
+                "type": "object",
+                "properties": {"message": {"type": "string"}},
+                "required": ["message"],
+            },
+            tool_arguments={"message": "No auth needed"},
+        )
+
+        outputs = []
+        async for name, data in block.run(
+            input_data, user_id=MOCK_USER_ID, credentials=None
+        ):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        assert outputs[0][1] == "No auth needed"

autogpt_platform/backend/backend/blocks/mcp/test_mcp.py

@@ -0,0 +1,619 @@
+"""
+Tests for MCP client and MCPToolBlock.
+"""
+
+import json
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from backend.blocks.mcp.block import MCPToolBlock
+from backend.blocks.mcp.client import MCPCallResult, MCPClient, MCPClientError
+from backend.util.test import execute_block_test
+
+# ── SSE parsing unit tests ───────────────────────────────────────────
+
+
+class TestSSEParsing:
+    """Tests for SSE (text/event-stream) response parsing."""
+
+    def test_parse_sse_simple(self):
+        sse = (
+            "event: message\n"
+            'data: {"jsonrpc":"2.0","result":{"tools":[]},"id":1}\n'
+            "\n"
+        )
+        body = MCPClient._parse_sse_response(sse)
+        assert body["result"] == {"tools": []}
+        assert body["id"] == 1
+
+    def test_parse_sse_with_notifications(self):
+        """SSE streams can contain notifications (no id) before the response."""
+        sse = (
+            "event: message\n"
+            'data: {"jsonrpc":"2.0","method":"some/notification"}\n'
+            "\n"
+            "event: message\n"
+            'data: {"jsonrpc":"2.0","result":{"ok":true},"id":2}\n'
+            "\n"
+        )
+        body = MCPClient._parse_sse_response(sse)
+        assert body["result"] == {"ok": True}
+        assert body["id"] == 2
+
+    def test_parse_sse_error_response(self):
+        sse = (
+            "event: message\n"
+            'data: {"jsonrpc":"2.0","error":{"code":-32600,"message":"Bad Request"},"id":1}\n'
+        )
+        body = MCPClient._parse_sse_response(sse)
+        assert "error" in body
+        assert body["error"]["code"] == -32600
+
+    def test_parse_sse_no_data_raises(self):
+        with pytest.raises(MCPClientError, match="No JSON-RPC response found"):
+            MCPClient._parse_sse_response("event: message\n\n")
+
+    def test_parse_sse_empty_raises(self):
+        with pytest.raises(MCPClientError, match="No JSON-RPC response found"):
+            MCPClient._parse_sse_response("")
+
+    def test_parse_sse_ignores_non_data_lines(self):
+        sse = (
+            ": comment line\n"
+            "event: message\n"
+            "id: 123\n"
+            'data: {"jsonrpc":"2.0","result":"ok","id":1}\n'
+            "\n"
+        )
+        body = MCPClient._parse_sse_response(sse)
+        assert body["result"] == "ok"
+
+    def test_parse_sse_uses_last_response(self):
+        """If multiple responses exist, use the last one."""
+        sse = (
+            'data: {"jsonrpc":"2.0","result":"first","id":1}\n'
+            "\n"
+            'data: {"jsonrpc":"2.0","result":"second","id":2}\n'
+            "\n"
+        )
+        body = MCPClient._parse_sse_response(sse)
+        assert body["result"] == "second"
+
+
+# ── MCPClient unit tests ─────────────────────────────────────────────
+
+
+class TestMCPClient:
+    """Tests for the MCP HTTP client."""
+
+    def test_build_headers_without_auth(self):
+        client = MCPClient("https://mcp.example.com")
+        headers = client._build_headers()
+        assert "Authorization" not in headers
+        assert headers["Content-Type"] == "application/json"
+
+    def test_build_headers_with_auth(self):
+        client = MCPClient("https://mcp.example.com", auth_token="my-token")
+        headers = client._build_headers()
+        assert headers["Authorization"] == "Bearer my-token"
+
+    def test_build_jsonrpc_request(self):
+        client = MCPClient("https://mcp.example.com")
+        req = client._build_jsonrpc_request("tools/list")
+        assert req["jsonrpc"] == "2.0"
+        assert req["method"] == "tools/list"
+        assert "id" in req
+        assert "params" not in req
+
+    def test_build_jsonrpc_request_with_params(self):
+        client = MCPClient("https://mcp.example.com")
+        req = client._build_jsonrpc_request(
+            "tools/call", {"name": "test", "arguments": {"x": 1}}
+        )
+        assert req["params"] == {"name": "test", "arguments": {"x": 1}}
+
+    def test_request_id_increments(self):
+        client = MCPClient("https://mcp.example.com")
+        req1 = client._build_jsonrpc_request("tools/list")
+        req2 = client._build_jsonrpc_request("tools/list")
+        assert req2["id"] > req1["id"]
+
+    def test_server_url_trailing_slash_stripped(self):
+        client = MCPClient("https://mcp.example.com/mcp/")
+        assert client.server_url == "https://mcp.example.com/mcp"
+
+    @pytest.mark.asyncio
+    async def test_send_request_success(self):
+        client = MCPClient("https://mcp.example.com")
+
+        mock_response = AsyncMock()
+        mock_response.json.return_value = {
+            "jsonrpc": "2.0",
+            "result": {"tools": []},
+            "id": 1,
+        }
+
+        with patch.object(client, "_send_request", return_value={"tools": []}):
+            result = await client._send_request("tools/list")
+            assert result == {"tools": []}
+
+    @pytest.mark.asyncio
+    async def test_send_request_error(self):
+        client = MCPClient("https://mcp.example.com")
+
+        async def mock_send(*args, **kwargs):
+            raise MCPClientError("MCP server error [-32600]: Invalid Request")
+
+        with patch.object(client, "_send_request", side_effect=mock_send):
+            with pytest.raises(MCPClientError, match="Invalid Request"):
+                await client._send_request("tools/list")
+
+    @pytest.mark.asyncio
+    async def test_list_tools(self):
+        client = MCPClient("https://mcp.example.com")
+
+        mock_result = {
+            "tools": [
+                {
+                    "name": "get_weather",
+                    "description": "Get current weather for a city",
+                    "inputSchema": {
+                        "type": "object",
+                        "properties": {"city": {"type": "string"}},
+                        "required": ["city"],
+                    },
+                },
+                {
+                    "name": "search",
+                    "description": "Search the web",
+                    "inputSchema": {
+                        "type": "object",
+                        "properties": {"query": {"type": "string"}},
+                        "required": ["query"],
+                    },
+                },
+            ]
+        }
+
+        with patch.object(client, "_send_request", return_value=mock_result):
+            tools = await client.list_tools()
+
+        assert len(tools) == 2
+        assert tools[0].name == "get_weather"
+        assert tools[0].description == "Get current weather for a city"
+        assert tools[0].input_schema["properties"]["city"]["type"] == "string"
+        assert tools[1].name == "search"
+
+    @pytest.mark.asyncio
+    async def test_list_tools_empty(self):
+        client = MCPClient("https://mcp.example.com")
+
+        with patch.object(client, "_send_request", return_value={"tools": []}):
+            tools = await client.list_tools()
+
+        assert tools == []
+
+    @pytest.mark.asyncio
+    async def test_list_tools_none_result(self):
+        client = MCPClient("https://mcp.example.com")
+
+        with patch.object(client, "_send_request", return_value=None):
+            tools = await client.list_tools()
+
+        assert tools == []
+
+    @pytest.mark.asyncio
+    async def test_call_tool_success(self):
+        client = MCPClient("https://mcp.example.com")
+
+        mock_result = {
+            "content": [
+                {"type": "text", "text": json.dumps({"temp": 20, "city": "London"})}
+            ],
+            "isError": False,
+        }
+
+        with patch.object(client, "_send_request", return_value=mock_result):
+            result = await client.call_tool("get_weather", {"city": "London"})
+
+        assert not result.is_error
+        assert len(result.content) == 1
+        assert result.content[0]["type"] == "text"
+
+    @pytest.mark.asyncio
+    async def test_call_tool_error(self):
+        client = MCPClient("https://mcp.example.com")
+
+        mock_result = {
+            "content": [{"type": "text", "text": "City not found"}],
+            "isError": True,
+        }
+
+        with patch.object(client, "_send_request", return_value=mock_result):
+            result = await client.call_tool("get_weather", {"city": "???"})
+
+        assert result.is_error
+
+    @pytest.mark.asyncio
+    async def test_call_tool_none_result(self):
+        client = MCPClient("https://mcp.example.com")
+
+        with patch.object(client, "_send_request", return_value=None):
+            result = await client.call_tool("get_weather", {"city": "London"})
+
+        assert result.is_error
+
+    @pytest.mark.asyncio
+    async def test_initialize(self):
+        client = MCPClient("https://mcp.example.com")
+
+        mock_result = {
+            "protocolVersion": "2025-03-26",
+            "capabilities": {"tools": {}},
+            "serverInfo": {"name": "test-server", "version": "1.0.0"},
+        }
+
+        with (
+            patch.object(client, "_send_request", return_value=mock_result) as mock_req,
+            patch.object(client, "_send_notification") as mock_notif,
+        ):
+            result = await client.initialize()
+
+        mock_req.assert_called_once()
+        mock_notif.assert_called_once_with("notifications/initialized")
+        assert result["protocolVersion"] == "2025-03-26"
+
+
+# ── MCPToolBlock unit tests ──────────────────────────────────────────
+
+MOCK_USER_ID = "test-user-123"
+
+
+class TestMCPToolBlock:
+    """Tests for the MCPToolBlock."""
+
+    def test_block_instantiation(self):
+        block = MCPToolBlock()
+        assert block.id == "a0a4b1c2-d3e4-4f56-a7b8-c9d0e1f2a3b4"
+        assert block.name == "MCPToolBlock"
+
+    def test_input_schema_has_required_fields(self):
+        block = MCPToolBlock()
+        schema = block.input_schema.jsonschema()
+        props = schema.get("properties", {})
+        assert "server_url" in props
+        assert "selected_tool" in props
+        assert "tool_arguments" in props
+        assert "credentials" in props
+
+    def test_output_schema(self):
+        block = MCPToolBlock()
+        schema = block.output_schema.jsonschema()
+        props = schema.get("properties", {})
+        assert "result" in props
+        assert "error" in props
+
+    def test_get_input_schema_with_tool_schema(self):
+        tool_schema = {
+            "type": "object",
+            "properties": {"query": {"type": "string"}},
+            "required": ["query"],
+        }
+        data = {"tool_input_schema": tool_schema}
+        result = MCPToolBlock.Input.get_input_schema(data)
+        assert result == tool_schema
+
+    def test_get_input_schema_without_tool_schema(self):
+        result = MCPToolBlock.Input.get_input_schema({})
+        assert result == {}
+
+    def test_get_input_defaults(self):
+        data = {"tool_arguments": {"city": "London"}}
+        result = MCPToolBlock.Input.get_input_defaults(data)
+        assert result == {"city": "London"}
+
+    def test_get_missing_input(self):
+        data = {
+            "tool_input_schema": {
+                "type": "object",
+                "properties": {
+                    "city": {"type": "string"},
+                    "units": {"type": "string"},
+                },
+                "required": ["city", "units"],
+            },
+            "tool_arguments": {"city": "London"},
+        }
+        missing = MCPToolBlock.Input.get_missing_input(data)
+        assert missing == {"units"}
+
+    def test_get_missing_input_all_present(self):
+        data = {
+            "tool_input_schema": {
+                "type": "object",
+                "properties": {"city": {"type": "string"}},
+                "required": ["city"],
+            },
+            "tool_arguments": {"city": "London"},
+        }
+        missing = MCPToolBlock.Input.get_missing_input(data)
+        assert missing == set()
+
+    @pytest.mark.asyncio
+    async def test_run_with_mock(self):
+        """Test the block using the built-in test infrastructure."""
+        block = MCPToolBlock()
+        await execute_block_test(block)
+
+    @pytest.mark.asyncio
+    async def test_run_missing_server_url(self):
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="",
+            selected_tool="test",
+        )
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+        assert outputs == [("error", "MCP server URL is required")]
+
+    @pytest.mark.asyncio
+    async def test_run_missing_tool(self):
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="https://mcp.example.com/mcp",
+            selected_tool="",
+        )
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+        assert outputs == [
+            ("error", "No tool selected. Please select a tool from the dropdown.")
+        ]
+
+    @pytest.mark.asyncio
+    async def test_run_success(self):
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="https://mcp.example.com/mcp",
+            selected_tool="get_weather",
+            tool_input_schema={
+                "type": "object",
+                "properties": {"city": {"type": "string"}},
+            },
+            tool_arguments={"city": "London"},
+        )
+
+        async def mock_call(*args, **kwargs):
+            return {"temp": 20, "city": "London"}
+
+        block._call_mcp_tool = mock_call  # type: ignore
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert len(outputs) == 1
+        assert outputs[0][0] == "result"
+        assert outputs[0][1] == {"temp": 20, "city": "London"}
+
+    @pytest.mark.asyncio
+    async def test_run_mcp_error(self):
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="https://mcp.example.com/mcp",
+            selected_tool="bad_tool",
+        )
+
+        async def mock_call(*args, **kwargs):
+            raise MCPClientError("Tool not found")
+
+        block._call_mcp_tool = mock_call  # type: ignore
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert outputs[0][0] == "error"
+        assert "Tool not found" in outputs[0][1]
+
+    @pytest.mark.asyncio
+    async def test_call_mcp_tool_parses_json_text(self):
+        block = MCPToolBlock()
+
+        mock_result = MCPCallResult(
+            content=[
+                {"type": "text", "text": '{"temp": 20}'},
+            ],
+            is_error=False,
+        )
+
+        async def mock_init(self):
+            return {}
+
+        async def mock_call(self, name, args):
+            return mock_result
+
+        with (
+            patch.object(MCPClient, "initialize", mock_init),
+            patch.object(MCPClient, "call_tool", mock_call),
+        ):
+            result = await block._call_mcp_tool(
+                "https://mcp.example.com", "test_tool", {}
+            )
+
+        assert result == {"temp": 20}
+
+    @pytest.mark.asyncio
+    async def test_call_mcp_tool_plain_text(self):
+        block = MCPToolBlock()
+
+        mock_result = MCPCallResult(
+            content=[
+                {"type": "text", "text": "Hello, world!"},
+            ],
+            is_error=False,
+        )
+
+        async def mock_init(self):
+            return {}
+
+        async def mock_call(self, name, args):
+            return mock_result
+
+        with (
+            patch.object(MCPClient, "initialize", mock_init),
+            patch.object(MCPClient, "call_tool", mock_call),
+        ):
+            result = await block._call_mcp_tool(
+                "https://mcp.example.com", "test_tool", {}
+            )
+
+        assert result == "Hello, world!"
+
+    @pytest.mark.asyncio
+    async def test_call_mcp_tool_multiple_content(self):
+        block = MCPToolBlock()
+
+        mock_result = MCPCallResult(
+            content=[
+                {"type": "text", "text": "Part 1"},
+                {"type": "text", "text": '{"part": 2}'},
+            ],
+            is_error=False,
+        )
+
+        async def mock_init(self):
+            return {}
+
+        async def mock_call(self, name, args):
+            return mock_result
+
+        with (
+            patch.object(MCPClient, "initialize", mock_init),
+            patch.object(MCPClient, "call_tool", mock_call),
+        ):
+            result = await block._call_mcp_tool(
+                "https://mcp.example.com", "test_tool", {}
+            )
+
+        assert result == ["Part 1", {"part": 2}]
+
+    @pytest.mark.asyncio
+    async def test_call_mcp_tool_error_result(self):
+        block = MCPToolBlock()
+
+        mock_result = MCPCallResult(
+            content=[{"type": "text", "text": "Something went wrong"}],
+            is_error=True,
+        )
+
+        async def mock_init(self):
+            return {}
+
+        async def mock_call(self, name, args):
+            return mock_result
+
+        with (
+            patch.object(MCPClient, "initialize", mock_init),
+            patch.object(MCPClient, "call_tool", mock_call),
+        ):
+            with pytest.raises(MCPClientError, match="returned an error"):
+                await block._call_mcp_tool("https://mcp.example.com", "test_tool", {})
+
+    @pytest.mark.asyncio
+    async def test_call_mcp_tool_image_content(self):
+        block = MCPToolBlock()
+
+        mock_result = MCPCallResult(
+            content=[
+                {
+                    "type": "image",
+                    "data": "base64data==",
+                    "mimeType": "image/png",
+                }
+            ],
+            is_error=False,
+        )
+
+        async def mock_init(self):
+            return {}
+
+        async def mock_call(self, name, args):
+            return mock_result
+
+        with (
+            patch.object(MCPClient, "initialize", mock_init),
+            patch.object(MCPClient, "call_tool", mock_call),
+        ):
+            result = await block._call_mcp_tool(
+                "https://mcp.example.com", "test_tool", {}
+            )
+
+        assert result == {
+            "type": "image",
+            "data": "base64data==",
+            "mimeType": "image/png",
+        }
+
+    @pytest.mark.asyncio
+    async def test_run_with_credentials(self):
+        """Verify the block uses OAuth2Credentials and passes auth token."""
+        from pydantic import SecretStr
+
+        from backend.data.model import OAuth2Credentials
+
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="https://mcp.example.com/mcp",
+            selected_tool="test_tool",
+        )
+
+        captured_tokens: list[str | None] = []
+
+        async def mock_call(server_url, tool_name, arguments, auth_token=None):
+            captured_tokens.append(auth_token)
+            return "ok"
+
+        block._call_mcp_tool = mock_call  # type: ignore
+
+        test_creds = OAuth2Credentials(
+            id="cred-123",
+            provider="mcp",
+            access_token=SecretStr("resolved-token"),
+            refresh_token=SecretStr(""),
+            scopes=[],
+            title="Test MCP credential",
+        )
+
+        async for _ in block.run(
+            input_data, user_id=MOCK_USER_ID, credentials=test_creds
+        ):
+            pass
+
+        assert captured_tokens == ["resolved-token"]
+
+    @pytest.mark.asyncio
+    async def test_run_without_credentials(self):
+        """Verify the block works without credentials (public server)."""
+        block = MCPToolBlock()
+        input_data = MCPToolBlock.Input(
+            server_url="https://mcp.example.com/mcp",
+            selected_tool="test_tool",
+        )
+
+        captured_tokens: list[str | None] = []
+
+        async def mock_call(server_url, tool_name, arguments, auth_token=None):
+            captured_tokens.append(auth_token)
+            return "ok"
+
+        block._call_mcp_tool = mock_call  # type: ignore
+
+        outputs = []
+        async for name, data in block.run(input_data, user_id=MOCK_USER_ID):
+            outputs.append((name, data))
+
+        assert captured_tokens == [None]
+        assert outputs == [("result", "ok")]

autogpt_platform/backend/backend/blocks/mcp/test_oauth.py

@@ -0,0 +1,242 @@
+"""
+Tests for MCP OAuth handler.
+"""
+
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+from pydantic import SecretStr
+
+from backend.blocks.mcp.client import MCPClient
+from backend.blocks.mcp.oauth import MCPOAuthHandler
+from backend.data.model import OAuth2Credentials
+
+
+def _mock_response(json_data: dict, status: int = 200) -> MagicMock:
+    """Create a mock Response with synchronous json() (matching Requests.Response)."""
+    resp = MagicMock()
+    resp.status = status
+    resp.ok = 200 <= status < 300
+    resp.json.return_value = json_data
+    return resp
+
+
+class TestMCPOAuthHandler:
+    """Tests for the MCPOAuthHandler."""
+
+    def _make_handler(self, **overrides) -> MCPOAuthHandler:
+        defaults = {
+            "client_id": "test-client-id",
+            "client_secret": "test-client-secret",
+            "redirect_uri": "https://app.example.com/callback",
+            "authorize_url": "https://auth.example.com/authorize",
+            "token_url": "https://auth.example.com/token",
+        }
+        defaults.update(overrides)
+        return MCPOAuthHandler(**defaults)
+
+    def test_get_login_url_basic(self):
+        handler = self._make_handler()
+        url = handler.get_login_url(
+            scopes=["read", "write"],
+            state="random-state-token",
+            code_challenge="S256-challenge-value",
+        )
+
+        assert "https://auth.example.com/authorize?" in url
+        assert "response_type=code" in url
+        assert "client_id=test-client-id" in url
+        assert "state=random-state-token" in url
+        assert "code_challenge=S256-challenge-value" in url
+        assert "code_challenge_method=S256" in url
+        assert "scope=read+write" in url
+
+    def test_get_login_url_with_resource(self):
+        handler = self._make_handler(resource_url="https://mcp.example.com/mcp")
+        url = handler.get_login_url(
+            scopes=[], state="state", code_challenge="challenge"
+        )
+
+        assert "resource=https" in url
+
+    def test_get_login_url_without_pkce(self):
+        handler = self._make_handler()
+        url = handler.get_login_url(scopes=["read"], state="state", code_challenge=None)
+
+        assert "code_challenge" not in url
+        assert "code_challenge_method" not in url
+
+    @pytest.mark.asyncio
+    async def test_exchange_code_for_tokens(self):
+        handler = self._make_handler()
+
+        resp = _mock_response(
+            {
+                "access_token": "new-access-token",
+                "refresh_token": "new-refresh-token",
+                "expires_in": 3600,
+                "token_type": "Bearer",
+            }
+        )
+
+        with patch("backend.blocks.mcp.oauth.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.post = AsyncMock(return_value=resp)
+
+            creds = await handler.exchange_code_for_tokens(
+                code="auth-code",
+                scopes=["read"],
+                code_verifier="pkce-verifier",
+            )
+
+        assert isinstance(creds, OAuth2Credentials)
+        assert creds.access_token.get_secret_value() == "new-access-token"
+        assert creds.refresh_token is not None
+        assert creds.refresh_token.get_secret_value() == "new-refresh-token"
+        assert creds.scopes == ["read"]
+        assert creds.access_token_expires_at is not None
+
+    @pytest.mark.asyncio
+    async def test_refresh_tokens(self):
+        handler = self._make_handler()
+
+        existing_creds = OAuth2Credentials(
+            id="existing-id",
+            provider="mcp",
+            access_token=SecretStr("old-token"),
+            refresh_token=SecretStr("old-refresh"),
+            scopes=["read"],
+            title="test",
+        )
+
+        resp = _mock_response(
+            {
+                "access_token": "refreshed-token",
+                "refresh_token": "new-refresh",
+                "expires_in": 3600,
+            }
+        )
+
+        with patch("backend.blocks.mcp.oauth.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.post = AsyncMock(return_value=resp)
+
+            refreshed = await handler._refresh_tokens(existing_creds)
+
+        assert refreshed.id == "existing-id"
+        assert refreshed.access_token.get_secret_value() == "refreshed-token"
+        assert refreshed.refresh_token is not None
+        assert refreshed.refresh_token.get_secret_value() == "new-refresh"
+
+    @pytest.mark.asyncio
+    async def test_refresh_tokens_no_refresh_token(self):
+        handler = self._make_handler()
+
+        creds = OAuth2Credentials(
+            provider="mcp",
+            access_token=SecretStr("token"),
+            scopes=["read"],
+            title="test",
+        )
+
+        with pytest.raises(ValueError, match="No refresh token"):
+            await handler._refresh_tokens(creds)
+
+    @pytest.mark.asyncio
+    async def test_revoke_tokens_no_url(self):
+        handler = self._make_handler(revoke_url=None)
+
+        creds = OAuth2Credentials(
+            provider="mcp",
+            access_token=SecretStr("token"),
+            scopes=[],
+            title="test",
+        )
+
+        result = await handler.revoke_tokens(creds)
+        assert result is False
+
+    @pytest.mark.asyncio
+    async def test_revoke_tokens_with_url(self):
+        handler = self._make_handler(revoke_url="https://auth.example.com/revoke")
+
+        creds = OAuth2Credentials(
+            provider="mcp",
+            access_token=SecretStr("token"),
+            scopes=[],
+            title="test",
+        )
+
+        resp = _mock_response({}, status=200)
+
+        with patch("backend.blocks.mcp.oauth.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.post = AsyncMock(return_value=resp)
+
+            result = await handler.revoke_tokens(creds)
+
+        assert result is True
+
+
+class TestMCPClientDiscovery:
+    """Tests for MCPClient OAuth metadata discovery."""
+
+    @pytest.mark.asyncio
+    async def test_discover_auth_found(self):
+        client = MCPClient("https://mcp.example.com/mcp")
+
+        metadata = {
+            "authorization_servers": ["https://auth.example.com"],
+            "resource": "https://mcp.example.com/mcp",
+        }
+
+        resp = _mock_response(metadata, status=200)
+
+        with patch("backend.blocks.mcp.client.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.get = AsyncMock(return_value=resp)
+
+            result = await client.discover_auth()
+
+        assert result is not None
+        assert result["authorization_servers"] == ["https://auth.example.com"]
+
+    @pytest.mark.asyncio
+    async def test_discover_auth_not_found(self):
+        client = MCPClient("https://mcp.example.com/mcp")
+
+        resp = _mock_response({}, status=404)
+
+        with patch("backend.blocks.mcp.client.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.get = AsyncMock(return_value=resp)
+
+            result = await client.discover_auth()
+
+        assert result is None
+
+    @pytest.mark.asyncio
+    async def test_discover_auth_server_metadata(self):
+        client = MCPClient("https://mcp.example.com/mcp")
+
+        server_metadata = {
+            "issuer": "https://auth.example.com",
+            "authorization_endpoint": "https://auth.example.com/authorize",
+            "token_endpoint": "https://auth.example.com/token",
+            "registration_endpoint": "https://auth.example.com/register",
+            "code_challenge_methods_supported": ["S256"],
+        }
+
+        resp = _mock_response(server_metadata, status=200)
+
+        with patch("backend.blocks.mcp.client.Requests") as MockRequests:
+            instance = MockRequests.return_value
+            instance.get = AsyncMock(return_value=resp)
+
+            result = await client.discover_auth_server_metadata(
+                "https://auth.example.com"
+            )
+
+        assert result is not None
+        assert result["authorization_endpoint"] == "https://auth.example.com/authorize"
+        assert result["token_endpoint"] == "https://auth.example.com/token"

autogpt_platform/backend/backend/blocks/mcp/test_server.py

@@ -0,0 +1,162 @@
+"""
+Minimal MCP server for integration testing.
+
+Implements the MCP Streamable HTTP transport (JSON-RPC 2.0 over HTTP POST)
+with a few sample tools. Runs on localhost with a random available port.
+"""
+
+import json
+import logging
+
+from aiohttp import web
+
+logger = logging.getLogger(__name__)
+
+# Sample tools this test server exposes
+TEST_TOOLS = [
+    {
+        "name": "get_weather",
+        "description": "Get current weather for a city",
+        "inputSchema": {
+            "type": "object",
+            "properties": {
+                "city": {
+                    "type": "string",
+                    "description": "City name",
+                },
+            },
+            "required": ["city"],
+        },
+    },
+    {
+        "name": "add_numbers",
+        "description": "Add two numbers together",
+        "inputSchema": {
+            "type": "object",
+            "properties": {
+                "a": {"type": "number", "description": "First number"},
+                "b": {"type": "number", "description": "Second number"},
+            },
+            "required": ["a", "b"],
+        },
+    },
+    {
+        "name": "echo",
+        "description": "Echo back the input message",
+        "inputSchema": {
+            "type": "object",
+            "properties": {
+                "message": {"type": "string", "description": "Message to echo"},
+            },
+            "required": ["message"],
+        },
+    },
+]
+
+
+def _handle_initialize(params: dict) -> dict:
+    return {
+        "protocolVersion": "2025-03-26",
+        "capabilities": {"tools": {"listChanged": False}},
+        "serverInfo": {"name": "test-mcp-server", "version": "1.0.0"},
+    }
+
+
+def _handle_tools_list(params: dict) -> dict:
+    return {"tools": TEST_TOOLS}
+
+
+def _handle_tools_call(params: dict) -> dict:
+    tool_name = params.get("name", "")
+    arguments = params.get("arguments", {})
+
+    if tool_name == "get_weather":
+        city = arguments.get("city", "Unknown")
+        return {
+            "content": [
+                {
+                    "type": "text",
+                    "text": json.dumps(
+                        {"city": city, "temperature": 22, "condition": "sunny"}
+                    ),
+                }
+            ],
+        }
+
+    elif tool_name == "add_numbers":
+        a = arguments.get("a", 0)
+        b = arguments.get("b", 0)
+        return {
+            "content": [{"type": "text", "text": json.dumps({"result": a + b})}],
+        }
+
+    elif tool_name == "echo":
+        message = arguments.get("message", "")
+        return {
+            "content": [{"type": "text", "text": message}],
+        }
+
+    else:
+        return {
+            "content": [{"type": "text", "text": f"Unknown tool: {tool_name}"}],
+            "isError": True,
+        }
+
+
+HANDLERS = {
+    "initialize": _handle_initialize,
+    "tools/list": _handle_tools_list,
+    "tools/call": _handle_tools_call,
+}
+
+
+async def handle_mcp_request(request: web.Request) -> web.Response:
+    """Handle incoming MCP JSON-RPC 2.0 requests."""
+    # Check auth if configured
+    expected_token = request.app.get("auth_token")
+    if expected_token:
+        auth_header = request.headers.get("Authorization", "")
+        if auth_header != f"Bearer {expected_token}":
+            return web.json_response(
+                {
+                    "jsonrpc": "2.0",
+                    "error": {"code": -32001, "message": "Unauthorized"},
+                    "id": None,
+                },
+                status=401,
+            )
+
+    body = await request.json()
+
+    # Handle notifications (no id field) — just acknowledge
+    if "id" not in body:
+        return web.Response(status=202)
+
+    method = body.get("method", "")
+    params = body.get("params", {})
+    request_id = body.get("id")
+
+    handler = HANDLERS.get(method)
+    if not handler:
+        return web.json_response(
+            {
+                "jsonrpc": "2.0",
+                "error": {
+                    "code": -32601,
+                    "message": f"Method not found: {method}",
+                },
+                "id": request_id,
+            }
+        )
+
+    result = handler(params)
+    return web.json_response({"jsonrpc": "2.0", "result": result, "id": request_id})
+
+
+def create_test_mcp_app(auth_token: str | None = None) -> web.Application:
+    """Create an aiohttp app that acts as an MCP server."""
+    app = web.Application()
+    app.router.add_post("/mcp", handle_mcp_request)
+    if auth_token:
+        app["auth_token"] = auth_token
+    return app

autogpt_platform/backend/backend/data/graph.py

@@ -39,6 +39,7 @@ from backend.util import type as type_utils
 from backend.util.exceptions import GraphNotAccessibleError, GraphNotInLibraryError
 from backend.util.json import SafeJson
 from backend.util.models import Pagination
+from backend.util.request import parse_url
 
 from .block import (
     AnyBlockSchema,
@@ -518,6 +519,21 @@ class GraphModel(Graph, GraphMeta):
                 "required": ["id", "provider", "type"],
             }
 
+            # Add a descriptive display title when URL-based discriminator values
+            # are present (e.g. "MCP: mcp.sentry.dev" instead of just "Mcp")
+            if (
+                field_info.discriminator
+                and not field_info.discriminator_mapping
+                and field_info.discriminator_values
+            ):
+                hostnames = sorted(
+                    parse_url(str(v)).netloc for v in field_info.discriminator_values
+                )
+                base_name = (
+                    next(iter(field_info.provider), "").replace("_", " ").upper()
+                )
+                field_schema["display_name"] = f"{base_name}: {', '.join(hostnames)}"
+
             # Add other (optional) field info items
             field_schema.update(
                 field_info.model_dump(

autogpt_platform/backend/backend/data/graph_test.py

@@ -463,3 +463,108 @@ def test_node_credentials_optional_with_other_metadata():
     assert node.credentials_optional is True
     assert node.metadata["position"] == {"x": 100, "y": 200}
     assert node.metadata["customized_name"] == "My Custom Node"
+
+
+# ============================================================================
+# Tests for MCP Credential Deduplication
+# ============================================================================
+
+
+def test_mcp_credential_combine_different_servers():
+    """Two MCP credential fields with different server URLs should produce
+    separate entries when combined (not merged into one)."""
+    from backend.data.model import CredentialsFieldInfo
+    from backend.integrations.providers import ProviderName
+
+    field_sentry = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+        discriminator_values={"https://mcp.sentry.dev/mcp"},
+    )
+    field_linear = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+        discriminator_values={"https://mcp.linear.app/mcp"},
+    )
+
+    combined = CredentialsFieldInfo.combine(
+        (field_sentry, ("node-sentry", "credentials")),
+        (field_linear, ("node-linear", "credentials")),
+    )
+
+    # Should produce 2 separate credential entries
+    assert len(combined) == 2, (
+        f"Expected 2 credential entries for 2 MCP blocks with different servers, "
+        f"got {len(combined)}: {list(combined.keys())}"
+    )
+
+    # Each entry should contain the server hostname in its key
+    keys = list(combined.keys())
+    assert any(
+        "mcp.sentry.dev" in k for k in keys
+    ), f"Expected 'mcp.sentry.dev' in one key, got {keys}"
+    assert any(
+        "mcp.linear.app" in k for k in keys
+    ), f"Expected 'mcp.linear.app' in one key, got {keys}"
+
+
+def test_mcp_credential_combine_same_server():
+    """Two MCP credential fields with the same server URL should be combined
+    into one credential entry."""
+    from backend.data.model import CredentialsFieldInfo
+    from backend.integrations.providers import ProviderName
+
+    field_a = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+        discriminator_values={"https://mcp.sentry.dev/mcp"},
+    )
+    field_b = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+        discriminator_values={"https://mcp.sentry.dev/mcp"},
+    )
+
+    combined = CredentialsFieldInfo.combine(
+        (field_a, ("node-a", "credentials")),
+        (field_b, ("node-b", "credentials")),
+    )
+
+    # Should produce 1 credential entry (same server URL)
+    assert len(combined) == 1, (
+        f"Expected 1 credential entry for 2 MCP blocks with same server, "
+        f"got {len(combined)}: {list(combined.keys())}"
+    )
+
+
+def test_mcp_credential_combine_no_discriminator_values():
+    """MCP credential fields without discriminator_values should be merged
+    into a single entry (backwards compat for blocks without server_url set)."""
+    from backend.data.model import CredentialsFieldInfo
+    from backend.integrations.providers import ProviderName
+
+    field_a = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+    )
+    field_b = CredentialsFieldInfo(
+        credentials_provider=frozenset([ProviderName.MCP]),
+        credentials_types=frozenset(["oauth2"]),
+        discriminator="server_url",
+    )
+
+    combined = CredentialsFieldInfo.combine(
+        (field_a, ("node-a", "credentials")),
+        (field_b, ("node-b", "credentials")),
+    )
+
+    # Should produce 1 entry (no URL differentiation)
+    assert len(combined) == 1, (
+        f"Expected 1 credential entry for MCP blocks without discriminator_values, "
+        f"got {len(combined)}: {list(combined.keys())}"
+    )

autogpt_platform/backend/backend/data/model.py

@@ -603,11 +603,16 @@ class CredentialsFieldInfo(BaseModel, Generic[CP, CT]):
         ] = defaultdict(list)
 
         for field, key in fields:
-            if field.provider == frozenset([ProviderName.HTTP]):
+            if (
-                # HTTP host-scoped credentials can have different hosts that reqires different credential sets.
+                field.discriminator
-                # Group by host extracted from the URL
+                and not field.discriminator_mapping
+                and field.discriminator_values
+            ):
+                # URL-based discrimination (e.g. HTTP host-scoped, MCP server URL):
+                # Each unique host gets its own credential entry.
+                provider_prefix = next(iter(field.provider))
                 providers = frozenset(
-                    [cast(CP, "http")]
+                    [cast(CP, str(provider_prefix))]
                     + [
                         cast(CP, parse_url(str(value)).netloc)
                         for value in field.discriminator_values

autogpt_platform/backend/backend/executor/manager.py

@@ -18,6 +18,7 @@ from redis.asyncio.lock import Lock as AsyncRedisLock
 
 from backend.blocks.agent import AgentExecutorBlock
 from backend.blocks.io import AgentOutputBlock
+from backend.blocks.mcp.block import MCPToolBlock
 from backend.data import redis_client as redis
 from backend.data.block import (
     BlockInput,
@@ -229,6 +230,10 @@ async def execute_node(
             _input_data.nodes_input_masks = nodes_input_masks
         _input_data.user_id = user_id
         input_data = _input_data.model_dump()
+    elif isinstance(node_block, MCPToolBlock):
+        _mcp_data = MCPToolBlock.Input(**node.input_default)
+        _mcp_data.tool_arguments = input_data
+        input_data = _mcp_data.model_dump()
     data.inputs = input_data
 
     # Execute the node
@@ -265,7 +270,12 @@ async def execute_node(
 
     # Handle regular credentials fields
     for field_name, input_type in input_model.get_credentials_fields().items():
-        credentials_meta = input_type(**input_data[field_name])
+        field_value = input_data.get(field_name)
+        if not field_value or (
+            isinstance(field_value, dict) and not field_value.get("id")
+        ):
+            continue  # No credentials configured — block runs without
+        credentials_meta = input_type(**field_value)
         credentials, lock = await creds_manager.acquire(user_id, credentials_meta.id)
         creds_locks.append(lock)
         extra_exec_kwargs[field_name] = credentials

autogpt_platform/backend/backend/executor/utils.py

@@ -339,16 +339,16 @@ async def _validate_node_input_credentials(
                 ] = "Invalid credentials: type/provider mismatch"
                 continue
 
-        # If node has optional credentials and any are missing, mark for skipping
+        # If node has optional credentials and any are missing, allow running without.
-        # But only if there are no other errors for this node
+        # The executor will pass credentials=None to the block's run().
         if (
             has_missing_credentials
             and node.credentials_optional
             and node.id not in credential_errors
         ):
-            nodes_to_skip.add(node.id)
             logger.info(
-                f"Node #{node.id} will be skipped: optional credentials not configured"
+                f"Node #{node.id}: optional credentials not configured, "
+                "running without"
             )
 
     return credential_errors, nodes_to_skip

autogpt_platform/backend/backend/integrations/providers.py

@@ -30,6 +30,7 @@ class ProviderName(str, Enum):
     IDEOGRAM = "ideogram"
     JINA = "jina"
     LLAMA_API = "llama_api"
+    MCP = "mcp"
     MEDIUM = "medium"
     MEM0 = "mem0"
     NOTION = "notion"

autogpt_platform/backend/backend/util/request.py

@@ -101,7 +101,7 @@ class HostResolver(abc.AbstractResolver):
     def __init__(self, ssl_hostname: str, ip_addresses: list[str]):
         self.ssl_hostname = ssl_hostname
         self.ip_addresses = ip_addresses
-        self._default = aiohttp.AsyncResolver()
+        self._default = aiohttp.ThreadedResolver()
 
     async def resolve(self, host, port=0, family=socket.AF_INET):
         if host == self.ssl_hostname:
@@ -467,7 +467,7 @@ class Requests:
             resolver = HostResolver(ssl_hostname=hostname, ip_addresses=ip_addresses)
             ssl_context = ssl.create_default_context()
             connector = aiohttp.TCPConnector(resolver=resolver, ssl=ssl_context)
-        session_kwargs = {}
+        session_kwargs: dict = {}
         if connector:
             session_kwargs["connector"] = connector
 

autogpt_platform/frontend/src/app/(platform)/auth/integrations/mcp_callback/route.ts

@@ -0,0 +1,96 @@
+import { NextResponse } from "next/server";
+
+/**
+ * Safely encode a value as JSON for embedding in a script tag.
+ * Escapes characters that could break out of the script context to prevent XSS.
+ */
+function safeJsonStringify(value: unknown): string {
+  return JSON.stringify(value)
+    .replace(/</g, "\\u003c")
+    .replace(/>/g, "\\u003e")
+    .replace(/&/g, "\\u0026");
+}
+
+// MCP-specific OAuth callback route.
+//
+// Unlike the generic oauth_callback which relies on window.opener.postMessage,
+// this route uses BroadcastChannel as the PRIMARY communication method.
+// This is critical because cross-origin OAuth flows (e.g. Sentry → localhost)
+// often lose window.opener due to COOP (Cross-Origin-Opener-Policy) headers.
+//
+// BroadcastChannel works across all same-origin tabs/popups regardless of opener.
+export async function GET(request: Request) {
+  const { searchParams } = new URL(request.url);
+  const code = searchParams.get("code");
+  const state = searchParams.get("state");
+
+  const success = Boolean(code && state);
+  const message = success
+    ? { success: true, code, state }
+    : {
+        success: false,
+        message: `Missing parameters: ${searchParams.toString()}`,
+      };
+
+  return new NextResponse(
+    `<!DOCTYPE html>
+<html>
+  <head><title>MCP Sign-in</title></head>
+  <body style="font-family: system-ui, -apple-system, sans-serif; display: flex; align-items: center; justify-content: center; min-height: 100vh; margin: 0; background: #f9fafb;">
+    <div style="text-align: center; max-width: 400px; padding: 2rem;">
+      <div id="spinner" style="margin: 0 auto 1rem; width: 32px; height: 32px; border: 3px solid #e5e7eb; border-top-color: #3b82f6; border-radius: 50%; animation: spin 0.8s linear infinite;"></div>
+      <p id="status" style="color: #374151; font-size: 16px;">Completing sign-in...</p>
+    </div>
+    <style>@keyframes spin { to { transform: rotate(360deg); } }</style>
+    <script>
+      (function() {
+        var msg = ${safeJsonStringify(message)};
+        var sent = false;
+
+        // Method 1: BroadcastChannel (reliable across tabs/popups, no opener needed)
+        try {
+          var bc = new BroadcastChannel("mcp_oauth");
+          bc.postMessage({ type: "mcp_oauth_result", success: msg.success, code: msg.code, state: msg.state, message: msg.message });
+          bc.close();
+          sent = true;
+        } catch(e) { console.warn("BroadcastChannel failed:", e); }
+
+        // Method 2: window.opener.postMessage (fallback for same-origin popups)
+        try {
+          if (window.opener && !window.opener.closed) {
+            window.opener.postMessage(
+              { message_type: "mcp_oauth_result", success: msg.success, code: msg.code, state: msg.state, message: msg.message },
+              window.location.origin
+            );
+            sent = true;
+          }
+        } catch(e) { console.warn("postMessage failed:", e); }
+
+        // Method 3: localStorage (most reliable cross-tab fallback)
+        try {
+          localStorage.setItem("mcp_oauth_result", JSON.stringify(msg));
+          sent = true;
+        } catch(e) { console.warn("localStorage failed:", e); }
+
+        var statusEl = document.getElementById("status");
+        var spinnerEl = document.getElementById("spinner");
+        spinnerEl.style.display = "none";
+
+        if (msg.success && sent) {
+          statusEl.textContent = "Sign-in complete! This window will close.";
+          statusEl.style.color = "#059669";
+          setTimeout(function() { window.close(); }, 1500);
+        } else if (msg.success) {
+          statusEl.textContent = "Sign-in successful! You can close this tab and return to the builder.";
+          statusEl.style.color = "#059669";
+        } else {
+          statusEl.textContent = "Sign-in failed: " + (msg.message || "Unknown error");
+          statusEl.style.color = "#dc2626";
+        }
+      })();
+    </script>
+  </body>
+</html>`,
+    { headers: { "Content-Type": "text/html" } },
+  );
+}

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/CustomNode.tsx

@@ -47,7 +47,10 @@ export type CustomNode = XYNode<CustomNodeData, "custom">;
 
 export const CustomNode: React.FC<NodeProps<CustomNode>> = React.memo(
   ({ data, id: nodeId, selected }) => {
-    const { inputSchema, outputSchema } = useCustomNode({ data, nodeId });
+    const { inputSchema, outputSchema, isMCPWithTool } = useCustomNode({
+      data,
+      nodeId,
+    });
 
     const isAgent = data.uiType === BlockUIType.AGENT;
 
@@ -98,6 +101,7 @@ export const CustomNode: React.FC<NodeProps<CustomNode>> = React.memo(
             jsonSchema={preprocessInputSchema(inputSchema)}
             nodeId={nodeId}
             uiType={data.uiType}
+            isMCPWithTool={isMCPWithTool}
             className={cn(
               "bg-white px-4",
               isWebhook && "pointer-events-none opacity-50",

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/components/NodeHeader.tsx

@@ -6,6 +6,7 @@ import {
   TooltipProvider,
   TooltipTrigger,
 } from "@/components/atoms/Tooltip/BaseTooltip";
+import { SpecialBlockID } from "@/lib/autogpt-server-api";
 import { beautifyString, cn } from "@/lib/utils";
 import { useState } from "react";
 import { CustomNodeData } from "../CustomNode";
@@ -20,8 +21,15 @@ type Props = {
 
 export const NodeHeader = ({ data, nodeId }: Props) => {
   const updateNodeData = useNodeStore((state) => state.updateNodeData);
+  const isMCPWithTool =
+    data.block_id === SpecialBlockID.MCP_TOOL &&
+    !!data.hardcodedValues?.selected_tool;
+
   const title =
     (data.metadata?.customized_name as string) ||
+    (isMCPWithTool
+      ? `${data.hardcodedValues.server_name || "MCP"}: ${beautifyString(data.hardcodedValues.selected_tool)}`
+      : null) ||
     data.hardcodedValues?.agent_name ||
     data.title;
 

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/useCustomNode.tsx

@@ -3,6 +3,30 @@ import { CustomNodeData } from "./CustomNode";
 import { BlockUIType } from "../../../types";
 import { useMemo } from "react";
 import { mergeSchemaForResolution } from "./helpers";
+import { SpecialBlockID } from "@/lib/autogpt-server-api";
+
+/**
+ * Build a dynamic input schema for MCP blocks.
+ *
+ * When a tool has been selected (tool_input_schema is populated), the block
+ * renders only the selected tool's input parameters. Credentials are NOT
+ * included because authentication is already handled by the MCP dialog's
+ * OAuth flow and stored server-side.
+ *
+ * Static fields like server_url, selected_tool, available_tools, and
+ * tool_arguments are hidden because they're pre-configured from the dialog.
+ */
+function buildMCPInputSchema(
+  toolInputSchema: Record<string, any>,
+): Record<string, any> {
+  return {
+    type: "object",
+    properties: {
+      ...(toolInputSchema.properties ?? {}),
+    },
+    required: [...(toolInputSchema.required ?? [])],
+  };
+}
 
 export const useCustomNode = ({
   data,
@@ -19,10 +43,15 @@ export const useCustomNode = ({
   );
 
   const isAgent = data.uiType === BlockUIType.AGENT;
+  const isMCPWithTool =
+    data.block_id === SpecialBlockID.MCP_TOOL &&
+    !!data.hardcodedValues?.tool_input_schema?.properties;
 
   const currentInputSchema = isAgent
     ? (data.hardcodedValues.input_schema ?? {})
-    : data.inputSchema;
+    : isMCPWithTool
+      ? buildMCPInputSchema(data.hardcodedValues.tool_input_schema)
+      : data.inputSchema;
   const currentOutputSchema = isAgent
     ? (data.hardcodedValues.output_schema ?? {})
     : data.outputSchema;
@@ -54,5 +83,6 @@ export const useCustomNode = ({
   return {
     inputSchema,
     outputSchema,
+    isMCPWithTool,
   };
 };

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/FormCreator.tsx

@@ -9,39 +9,63 @@ interface FormCreatorProps {
   jsonSchema: RJSFSchema;
   nodeId: string;
   uiType: BlockUIType;
+  /** When true the block is an MCP Tool with a selected tool. */
+  isMCPWithTool?: boolean;
   showHandles?: boolean;
   className?: string;
 }
 
 export const FormCreator: React.FC<FormCreatorProps> = React.memo(
-  ({ jsonSchema, nodeId, uiType, showHandles = true, className }) => {
+  ({
+    jsonSchema,
+    nodeId,
+    uiType,
+    isMCPWithTool = false,
+    showHandles = true,
+    className,
+  }) => {
     const updateNodeData = useNodeStore((state) => state.updateNodeData);
 
     const getHardCodedValues = useNodeStore(
       (state) => state.getHardCodedValues,
     );
 
+    const isAgent = uiType === BlockUIType.AGENT;
+
     const handleChange = ({ formData }: any) => {
       if ("credentials" in formData && !formData.credentials?.id) {
         delete formData.credentials;
       }
 
-      const updatedValues =
+      let updatedValues;
-        uiType === BlockUIType.AGENT
+      if (isAgent) {
-          ? {
+        updatedValues = {
-              ...getHardCodedValues(nodeId),
+          ...getHardCodedValues(nodeId),
-              inputs: formData,
+          inputs: formData,
-            }
+        };
-          : formData;
+      } else if (isMCPWithTool) {
+        // All form fields are tool arguments (credentials handled by dialog)
+        updatedValues = {
+          ...getHardCodedValues(nodeId),
+          tool_arguments: formData,
+        };
+      } else {
+        updatedValues = formData;
+      }
 
       updateNodeData(nodeId, { hardcodedValues: updatedValues });
     };
 
     const hardcodedValues = getHardCodedValues(nodeId);
-    const initialValues =
+
-      uiType === BlockUIType.AGENT
+    let initialValues;
-        ? (hardcodedValues.inputs ?? {})
+    if (isAgent) {
-        : hardcodedValues;
+      initialValues = hardcodedValues.inputs ?? {};
+    } else if (isMCPWithTool) {
+      initialValues = hardcodedValues.tool_arguments ?? {};
+    } else {
+      initialValues = hardcodedValues;
+    }
 
     return (
       <div

autogpt_platform/frontend/src/app/(platform)/build/components/NewControlPanel/NewBlockMenu/Block.tsx

@@ -1,7 +1,7 @@
 import { Button } from "@/components/__legacy__/ui/button";
 import { Skeleton } from "@/components/__legacy__/ui/skeleton";
 import { beautifyString, cn } from "@/lib/utils";
-import React, { ButtonHTMLAttributes } from "react";
+import React, { ButtonHTMLAttributes, useCallback, useState } from "react";
 import { highlightText } from "./helpers";
 import { PlusIcon } from "@phosphor-icons/react";
 import { BlockInfo } from "@/app/api/__generated__/models/blockInfo";
@@ -9,6 +9,12 @@ import { useControlPanelStore } from "../../../stores/controlPanelStore";
 import { blockDragPreviewStyle } from "./style";
 import { useReactFlow } from "@xyflow/react";
 import { useNodeStore } from "../../../stores/nodeStore";
+import { SpecialBlockID } from "@/lib/autogpt-server-api";
+import {
+  MCPToolDialog,
+  type MCPToolDialogResult,
+} from "@/app/(platform)/build/components/legacy-builder/MCPToolDialog";
+
 interface Props extends ButtonHTMLAttributes<HTMLButtonElement> {
   title?: string;
   description?: string;
@@ -33,22 +39,52 @@ export const Block: BlockComponent = ({
   );
   const { setViewport } = useReactFlow();
   const { addBlock } = useNodeStore();
+  const [mcpDialogOpen, setMcpDialogOpen] = useState(false);
+
+  const isMCPBlock = blockData.id === SpecialBlockID.MCP_TOOL;
+
+  const addBlockAndCenter = useCallback(
+    (block: BlockInfo, hardcodedValues?: Record<string, any>) => {
+      const customNode = addBlock(block, hardcodedValues);
+      setTimeout(() => {
+        setViewport(
+          {
+            x: -customNode.position.x * 0.8 + window.innerWidth / 2,
+            y: -customNode.position.y * 0.8 + (window.innerHeight - 400) / 2,
+            zoom: 0.8,
+          },
+          { duration: 500 },
+        );
+      }, 50);
+    },
+    [addBlock, setViewport],
+  );
+
+  const handleMCPToolConfirm = useCallback(
+    (result: MCPToolDialogResult) => {
+      addBlockAndCenter(blockData, {
+        server_url: result.serverUrl,
+        server_name: result.serverName,
+        selected_tool: result.selectedTool,
+        tool_input_schema: result.toolInputSchema,
+        available_tools: result.availableTools,
+        credentials: result.credentials ?? undefined,
+      });
+      setMcpDialogOpen(false);
+    },
+    [addBlockAndCenter, blockData],
+  );
 
   const handleClick = () => {
-    const customNode = addBlock(blockData);
+    if (isMCPBlock) {
-    setTimeout(() => {
+      setMcpDialogOpen(true);
-      setViewport(
+      return;
-        {
+    }
-          x: -customNode.position.x * 0.8 + window.innerWidth / 2,
+    addBlockAndCenter(blockData);
-          y: -customNode.position.y * 0.8 + (window.innerHeight - 400) / 2,
-          zoom: 0.8,
-        },
-        { duration: 500 },
-      );
-    }, 50);
   };
 
   const handleDragStart = (e: React.DragEvent<HTMLButtonElement>) => {
+    if (isMCPBlock) return;
     e.dataTransfer.effectAllowed = "copy";
     e.dataTransfer.setData("application/reactflow", JSON.stringify(blockData));
 
@@ -71,46 +107,56 @@ export const Block: BlockComponent = ({
     : undefined;
 
   return (
-    <Button
+    <>
-      draggable={true}
+      <Button
-      data-id={blockDataId}
+        draggable={!isMCPBlock}
-      className={cn(
+        data-id={blockDataId}
-        "group flex h-16 w-full min-w-[7.5rem] items-center justify-start space-x-3 whitespace-normal rounded-[0.75rem] bg-zinc-50 px-[0.875rem] py-[0.625rem] text-start shadow-none",
-        "hover:cursor-default hover:bg-zinc-100 focus:ring-0 active:bg-zinc-100 active:ring-1 active:ring-zinc-300 disabled:cursor-not-allowed",
-        className,
-      )}
-      onDragStart={handleDragStart}
-      onClick={handleClick}
-      {...rest}
-    >
-      <div className="flex flex-1 flex-col items-start gap-0.5">
-        {title && (
-          <span
-            className={cn(
-              "line-clamp-1 font-sans text-sm font-medium leading-[1.375rem] text-zinc-800 group-disabled:text-zinc-400",
-            )}
-          >
-            {highlightText(beautifyString(title), highlightedText)}
-          </span>
-        )}
-        {description && (
-          <span
-            className={cn(
-              "line-clamp-1 font-sans text-xs font-normal leading-5 text-zinc-500 group-disabled:text-zinc-400",
-            )}
-          >
-            {highlightText(description, highlightedText)}
-          </span>
-        )}
-      </div>
-      <div
         className={cn(
-          "flex h-7 w-7 items-center justify-center rounded-[0.5rem] bg-zinc-700 group-disabled:bg-zinc-400",
+          "group flex h-16 w-full min-w-[7.5rem] items-center justify-start space-x-3 whitespace-normal rounded-[0.75rem] bg-zinc-50 px-[0.875rem] py-[0.625rem] text-start shadow-none",
+          "hover:cursor-default hover:bg-zinc-100 focus:ring-0 active:bg-zinc-100 active:ring-1 active:ring-zinc-300 disabled:cursor-not-allowed",
+          isMCPBlock && "hover:cursor-pointer",
+          className,
         )}
+        onDragStart={handleDragStart}
+        onClick={handleClick}
+        {...rest}
       >
-        <PlusIcon className="h-5 w-5 text-zinc-50" />
+        <div className="flex flex-1 flex-col items-start gap-0.5">
-      </div>
+          {title && (
-    </Button>
+            <span
+              className={cn(
+                "line-clamp-1 font-sans text-sm font-medium leading-[1.375rem] text-zinc-800 group-disabled:text-zinc-400",
+              )}
+            >
+              {highlightText(beautifyString(title), highlightedText)}
+            </span>
+          )}
+          {description && (
+            <span
+              className={cn(
+                "line-clamp-1 font-sans text-xs font-normal leading-5 text-zinc-500 group-disabled:text-zinc-400",
+              )}
+            >
+              {highlightText(description, highlightedText)}
+            </span>
+          )}
+        </div>
+        <div
+          className={cn(
+            "flex h-7 w-7 items-center justify-center rounded-[0.5rem] bg-zinc-700 group-disabled:bg-zinc-400",
+          )}
+        >
+          <PlusIcon className="h-5 w-5 text-zinc-50" />
+        </div>
+      </Button>
+      {isMCPBlock && (
+        <MCPToolDialog
+          open={mcpDialogOpen}
+          onClose={() => setMcpDialogOpen(false)}
+          onConfirm={handleMCPToolConfirm}
+        />
+      )}
+    </>
   );
 };
 

autogpt_platform/frontend/src/app/(platform)/build/components/legacy-builder/BlocksControl.tsx

@@ -29,6 +29,10 @@ import {
   TooltipTrigger,
 } from "@/components/atoms/Tooltip/BaseTooltip";
 import { GraphMeta } from "@/lib/autogpt-server-api";
+import {
+  MCPToolDialog,
+  type MCPToolDialogResult,
+} from "@/app/(platform)/build/components/legacy-builder/MCPToolDialog";
 import jaro from "jaro-winkler";
 import { getV1GetSpecificGraph } from "@/app/api/__generated__/endpoints/graphs/graphs";
 import { okData } from "@/app/api/helpers";
@@ -94,6 +98,7 @@ export function BlocksControl({
   const [searchQuery, setSearchQuery] = useState("");
   const deferredSearchQuery = useDeferredValue(searchQuery);
   const [selectedCategory, setSelectedCategory] = useState<string | null>(null);
+  const [mcpDialogOpen, setMcpDialogOpen] = useState(false);
 
   const blocks = useSearchableBlocks(_blocks);
 
@@ -186,11 +191,32 @@ export function BlocksControl({
     setSelectedCategory(null);
   }, []);
 
+  const handleMCPToolConfirm = useCallback(
+    (result: MCPToolDialogResult) => {
+      addBlock(SpecialBlockID.MCP_TOOL, "MCPToolBlock", {
+        server_url: result.serverUrl,
+        server_name: result.serverName,
+        selected_tool: result.selectedTool,
+        tool_input_schema: result.toolInputSchema,
+        available_tools: result.availableTools,
+        credentials: result.credentials ?? undefined,
+      });
+      setMcpDialogOpen(false);
+    },
+    [addBlock],
+  );
+
   // Handler to add a block, fetching graph data on-demand for agent blocks
   const handleAddBlock = useCallback(
     async (block: _Block & { notAvailable: string | null }) => {
       if (block.notAvailable) return;
 
+      // For MCP blocks, open the configuration dialog instead of placing directly
+      if (block.id === SpecialBlockID.MCP_TOOL) {
+        setMcpDialogOpen(true);
+        return;
+      }
+
       // For agent blocks, fetch the full graph to get schemas
       if (block.uiType === BlockUIType.AGENT && block.hardcodedValues) {
         const graphID = block.hardcodedValues.graph_id as string;
@@ -230,162 +256,179 @@ export function BlocksControl({
   }, [blocks]);
 
   return (
-    <Popover
+    <>
-      open={pinBlocksPopover ? true : undefined}
+      <Popover
-      onOpenChange={(open) => open || resetFilters()}
+        open={pinBlocksPopover ? true : undefined}
-    >
+        onOpenChange={(open) => open || resetFilters()}
-      <Tooltip delayDuration={500}>
-        <TooltipTrigger asChild>
-          <PopoverTrigger asChild>
-            <Button
-              variant="ghost"
-              size="icon"
-              data-id="blocks-control-popover-trigger"
-              data-testid="blocks-control-blocks-button"
-              name="Blocks"
-              className="dark:hover:bg-slate-800"
-            >
-              <IconToyBrick />
-            </Button>
-          </PopoverTrigger>
-        </TooltipTrigger>
-        <TooltipContent side="right">Blocks</TooltipContent>
-      </Tooltip>
-      <PopoverContent
-        side="right"
-        sideOffset={22}
-        align="start"
-        className="absolute -top-3 w-[17rem] rounded-xl border-none p-0 shadow-none md:w-[30rem]"
-        data-id="blocks-control-popover-content"
       >
-        <Card className="p-3 pb-0 dark:bg-slate-900">
+        <Tooltip delayDuration={500}>
-          <CardHeader className="flex flex-col gap-x-8 gap-y-1 p-3 px-2">
+          <TooltipTrigger asChild>
-            <div className="items-center justify-between">
+            <PopoverTrigger asChild>
-              <Label
+              <Button
-                htmlFor="search-blocks"
+                variant="ghost"
-                className="whitespace-nowrap text-base font-bold text-black dark:text-white 2xl:text-xl"
+                size="icon"
-                data-id="blocks-control-label"
+                data-id="blocks-control-popover-trigger"
-                data-testid="blocks-control-blocks-label"
+                data-testid="blocks-control-blocks-button"
+                name="Blocks"
+                className="dark:hover:bg-slate-800"
               >
-                Blocks
+                <IconToyBrick />
-              </Label>
+              </Button>
-            </div>
+            </PopoverTrigger>
-            <div className="relative flex items-center">
+          </TooltipTrigger>
-              <MagnifyingGlassIcon className="absolute m-2 h-5 w-5 text-gray-500 dark:text-gray-400" />
+          <TooltipContent side="right">Blocks</TooltipContent>
-              <Input
+        </Tooltip>
-                id="search-blocks"
+        <PopoverContent
-                type="text"
+          side="right"
-                placeholder="Search blocks"
+          sideOffset={22}
-                value={searchQuery}
+          align="start"
-                onChange={(e) => setSearchQuery(e.target.value)}
+          className="absolute -top-3 w-[17rem] rounded-xl border-none p-0 shadow-none md:w-[30rem]"
-                className="rounded-lg px-8 py-5 dark:bg-slate-800 dark:text-white"
+          data-id="blocks-control-popover-content"
-                data-id="blocks-control-search-input"
+        >
-                autoComplete="off"
+          <Card className="p-3 pb-0 dark:bg-slate-900">
-              />
+            <CardHeader className="flex flex-col gap-x-8 gap-y-1 p-3 px-2">
-            </div>
+              <div className="items-center justify-between">
-            <div
+                <Label
-              className="mt-2 flex flex-wrap gap-2"
+                  htmlFor="search-blocks"
-              data-testid="blocks-categories-list"
+                  className="whitespace-nowrap text-base font-bold text-black dark:text-white 2xl:text-xl"
-            >
+                  data-id="blocks-control-label"
-              {categories.map((category) => {
+                  data-testid="blocks-control-blocks-label"
-                const color = getPrimaryCategoryColor([
-                  { category: category || "All", description: "" },
-                ]);
-                const colorClass =
-                  selectedCategory === category ? `${color}` : "";
-                return (
-                  <div
-                    key={category}
-                    data-testid="blocks-category"
-                    role="button"
-                    className={`cursor-pointer rounded-xl border px-2 py-2 text-xs font-medium dark:border-slate-700 dark:text-white ${colorClass}`}
-                    onClick={() =>
-                      setSelectedCategory(
-                        selectedCategory === category ? null : category,
-                      )
-                    }
-                  >
-                    {beautifyString((category || "All").toLowerCase())}
-                  </div>
-                );
-              })}
-            </div>
-          </CardHeader>
-          <CardContent className="overflow-scroll border-t border-t-gray-200 p-0 dark:border-t-slate-700">
-            <ScrollArea
-              className="h-[60vh] w-full"
-              data-id="blocks-control-scroll-area"
-            >
-              {filteredAvailableBlocks.map((block) => (
-                <Card
-                  key={block.uiKey || block.id}
-                  className={`m-2 my-4 flex h-20 shadow-none dark:border-slate-700 dark:bg-slate-800 dark:text-slate-100 dark:hover:bg-slate-700 ${
-                    block.notAvailable
-                      ? "cursor-not-allowed opacity-50"
-                      : "cursor-move hover:shadow-lg"
-                  }`}
-                  data-id={`block-card-${block.id}`}
-                  draggable={!block.notAvailable}
-                  onDragStart={(e) => {
-                    if (block.notAvailable) return;
-                    e.dataTransfer.effectAllowed = "copy";
-                    e.dataTransfer.setData(
-                      "application/reactflow",
-                      JSON.stringify({
-                        blockId: block.id,
-                        blockName: block.name,
-                        hardcodedValues: block?.hardcodedValues || {},
-                      }),
-                    );
-                  }}
-                  onClick={() => handleAddBlock(block)}
-                  title={block.notAvailable ?? undefined}
                 >
-                  <div
+                  Blocks
-                    className={`-ml-px h-full w-3 rounded-l-xl ${getPrimaryCategoryColor(block.categories)}`}
+                </Label>
-                  ></div>
+              </div>
-
+              <div className="relative flex items-center">
-                  <div className="mx-3 flex flex-1 items-center justify-between">
+                <MagnifyingGlassIcon className="absolute m-2 h-5 w-5 text-gray-500 dark:text-gray-400" />
-                    <div className="mr-2 min-w-0">
+                <Input
-                      <span
+                  id="search-blocks"
-                        className="block truncate pb-1 text-sm font-semibold dark:text-white"
+                  type="text"
-                        data-id={`block-name-${block.id}`}
+                  placeholder="Search blocks"
-                        data-type={block.uiType}
+                  value={searchQuery}
-                        data-testid={`block-name-${block.id}`}
+                  onChange={(e) => setSearchQuery(e.target.value)}
-                      >
+                  className="rounded-lg px-8 py-5 dark:bg-slate-800 dark:text-white"
-                        <TextRenderer
+                  data-id="blocks-control-search-input"
-                          value={beautifyString(block.name).replace(
+                  autoComplete="off"
-                            / Block$/,
+                />
-                            "",
+              </div>
-                          )}
+              <div
-                          truncateLengthLimit={45}
+                className="mt-2 flex flex-wrap gap-2"
-                        />
+                data-testid="blocks-categories-list"
-                      </span>
+              >
-                      <span
+                {categories.map((category) => {
-                        className="block break-all text-xs font-normal text-gray-500 dark:text-gray-400"
+                  const color = getPrimaryCategoryColor([
-                        data-testid={`block-description-${block.id}`}
+                    { category: category || "All", description: "" },
-                      >
+                  ]);
-                        <TextRenderer
+                  const colorClass =
-                          value={block.description}
+                    selectedCategory === category ? `${color}` : "";
-                          truncateLengthLimit={165}
+                  return (
-                        />
-                      </span>
-                    </div>
                     <div
-                      className="flex flex-shrink-0 items-center gap-1"
+                      key={category}
-                      data-id={`block-tooltip-${block.id}`}
+                      data-testid="blocks-category"
-                      data-testid={`block-add`}
+                      role="button"
+                      className={`cursor-pointer rounded-xl border px-2 py-2 text-xs font-medium dark:border-slate-700 dark:text-white ${colorClass}`}
+                      onClick={() =>
+                        setSelectedCategory(
+                          selectedCategory === category ? null : category,
+                        )
+                      }
                     >
-                      <PlusIcon className="h-6 w-6 rounded-lg bg-gray-200 stroke-black stroke-[0.5px] p-1 dark:bg-gray-700 dark:stroke-white" />
+                      {beautifyString((category || "All").toLowerCase())}
                     </div>
-                  </div>
+                  );
-                </Card>
+                })}
-              ))}
+              </div>
-            </ScrollArea>
+            </CardHeader>
-          </CardContent>
+            <CardContent className="overflow-scroll border-t border-t-gray-200 p-0 dark:border-t-slate-700">
-        </Card>
+              <ScrollArea
-      </PopoverContent>
+                className="h-[60vh] w-full"
-    </Popover>
+                data-id="blocks-control-scroll-area"
+              >
+                {filteredAvailableBlocks.map((block) => (
+                  <Card
+                    key={block.uiKey || block.id}
+                    className={`m-2 my-4 flex h-20 shadow-none dark:border-slate-700 dark:bg-slate-800 dark:text-slate-100 dark:hover:bg-slate-700 ${
+                      block.notAvailable
+                        ? "cursor-not-allowed opacity-50"
+                        : block.id === SpecialBlockID.MCP_TOOL
+                          ? "cursor-pointer hover:shadow-lg"
+                          : "cursor-move hover:shadow-lg"
+                    }`}
+                    data-id={`block-card-${block.id}`}
+                    draggable={
+                      !block.notAvailable &&
+                      block.id !== SpecialBlockID.MCP_TOOL
+                    }
+                    onDragStart={(e) => {
+                      if (
+                        block.notAvailable ||
+                        block.id === SpecialBlockID.MCP_TOOL
+                      )
+                        return;
+                      e.dataTransfer.effectAllowed = "copy";
+                      e.dataTransfer.setData(
+                        "application/reactflow",
+                        JSON.stringify({
+                          blockId: block.id,
+                          blockName: block.name,
+                          hardcodedValues: block?.hardcodedValues || {},
+                        }),
+                      );
+                    }}
+                    onClick={() => handleAddBlock(block)}
+                    title={block.notAvailable ?? undefined}
+                  >
+                    <div
+                      className={`-ml-px h-full w-3 rounded-l-xl ${getPrimaryCategoryColor(block.categories)}`}
+                    ></div>
+
+                    <div className="mx-3 flex flex-1 items-center justify-between">
+                      <div className="mr-2 min-w-0">
+                        <span
+                          className="block truncate pb-1 text-sm font-semibold dark:text-white"
+                          data-id={`block-name-${block.id}`}
+                          data-type={block.uiType}
+                          data-testid={`block-name-${block.id}`}
+                        >
+                          <TextRenderer
+                            value={beautifyString(block.name).replace(
+                              / Block$/,
+                              "",
+                            )}
+                            truncateLengthLimit={45}
+                          />
+                        </span>
+                        <span
+                          className="block break-all text-xs font-normal text-gray-500 dark:text-gray-400"
+                          data-testid={`block-description-${block.id}`}
+                        >
+                          <TextRenderer
+                            value={block.description}
+                            truncateLengthLimit={165}
+                          />
+                        </span>
+                      </div>
+                      <div
+                        className="flex flex-shrink-0 items-center gap-1"
+                        data-id={`block-tooltip-${block.id}`}
+                        data-testid={`block-add`}
+                      >
+                        <PlusIcon className="h-6 w-6 rounded-lg bg-gray-200 stroke-black stroke-[0.5px] p-1 dark:bg-gray-700 dark:stroke-white" />
+                      </div>
+                    </div>
+                  </Card>
+                ))}
+              </ScrollArea>
+            </CardContent>
+          </Card>
+        </PopoverContent>
+      </Popover>
+
+      <MCPToolDialog
+        open={mcpDialogOpen}
+        onClose={() => setMcpDialogOpen(false)}
+        onConfirm={handleMCPToolConfirm}
+      />
+    </>
   );
 }
 

autogpt_platform/frontend/src/app/(platform)/build/components/legacy-builder/CustomNode/CustomNode.tsx

@@ -21,6 +21,7 @@ import {
   GraphInputSchema,
   GraphOutputSchema,
   NodeExecutionResult,
+  SpecialBlockID,
 } from "@/lib/autogpt-server-api";
 import {
   beautifyString,
@@ -215,6 +216,26 @@ export const CustomNode = React.memo(
       }
     }
 
+    // MCP Tool block: display the selected tool's dynamic schema
+    const isMCPWithTool =
+      data.block_id === SpecialBlockID.MCP_TOOL &&
+      !!data.hardcodedValues?.tool_input_schema?.properties;
+
+    if (isMCPWithTool) {
+      // Show only the tool's input parameters. Credentials are NOT included
+      // because authentication is handled by the MCP dialog's OAuth flow
+      // and stored server-side.
+      const toolSchema = data.hardcodedValues.tool_input_schema;
+
+      data.inputSchema = {
+        type: "object",
+        properties: {
+          ...(toolSchema.properties ?? {}),
+        },
+        required: [...(toolSchema.required ?? [])],
+      } as BlockIORootSchema;
+    }
+
     const setHardcodedValues = useCallback(
       (values: any) => {
         updateNodeData(id, { hardcodedValues: values });
@@ -375,7 +396,9 @@ export const CustomNode = React.memo(
 
     const displayTitle =
       customTitle ||
-      beautifyString(data.blockType?.replace(/Block$/, "") || data.title);
+      (isMCPWithTool
+        ? `${data.hardcodedValues.server_name || "MCP"}: ${beautifyString(data.hardcodedValues.selected_tool || "")}`
+        : beautifyString(data.blockType?.replace(/Block$/, "") || data.title));
 
     useEffect(() => {
       isInitialSetup.current = false;
@@ -389,6 +412,15 @@ export const CustomNode = React.memo(
             data.inputSchema,
           ),
         });
+      } else if (isMCPWithTool) {
+        // MCP dialog already configured server_url, selected_tool, etc.
+        // Just ensure tool_arguments is initialized.
+        if (!data.hardcodedValues.tool_arguments) {
+          setHardcodedValues({
+            ...data.hardcodedValues,
+            tool_arguments: {},
+          });
+        }
       } else {
         setHardcodedValues(
           fillObjectDefaultsFromSchema(data.hardcodedValues, data.inputSchema),
@@ -525,8 +557,11 @@ export const CustomNode = React.memo(
           );
 
         default:
-          const getInputPropKey = (key: string) =>
+          const getInputPropKey = (key: string) => {
-            nodeType == BlockUIType.AGENT ? `inputs.${key}` : key;
+            if (nodeType == BlockUIType.AGENT) return `inputs.${key}`;
+            if (isMCPWithTool) return `tool_arguments.${key}`;
+            return key;
+          };
 
           return keys.map(([propKey, propSchema]) => {
             const isRequired = data.inputSchema.required?.includes(propKey);

autogpt_platform/frontend/src/app/(platform)/build/components/legacy-builder/MCPToolDialog.tsx

@@ -0,0 +1,689 @@
+"use client";
+
+import React, { useState, useCallback, useRef, useEffect } from "react";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/__legacy__/ui/dialog";
+import { Button } from "@/components/__legacy__/ui/button";
+import { Input } from "@/components/__legacy__/ui/input";
+import { Label } from "@/components/__legacy__/ui/label";
+import { LoadingSpinner } from "@/components/__legacy__/ui/loading";
+import { Badge } from "@/components/__legacy__/ui/badge";
+import { ScrollArea } from "@/components/__legacy__/ui/scroll-area";
+import { useBackendAPI } from "@/lib/autogpt-server-api/context";
+import type { CredentialsMetaInput, MCPTool } from "@/lib/autogpt-server-api";
+import { CaretDown } from "@phosphor-icons/react";
+
+export type MCPToolDialogResult = {
+  serverUrl: string;
+  serverName: string | null;
+  selectedTool: string;
+  toolInputSchema: Record<string, any>;
+  availableTools: Record<string, any>;
+  /** Credentials meta from OAuth flow, null for public servers. */
+  credentials: CredentialsMetaInput | null;
+};
+
+interface MCPToolDialogProps {
+  open: boolean;
+  onClose: () => void;
+  onConfirm: (result: MCPToolDialogResult) => void;
+}
+
+type DialogStep = "url" | "tool";
+
+const OAUTH_TIMEOUT_MS = 5 * 60 * 1000; // 5 minutes
+
+export function MCPToolDialog({
+  open,
+  onClose,
+  onConfirm,
+}: MCPToolDialogProps) {
+  const api = useBackendAPI();
+
+  const [step, setStep] = useState<DialogStep>("url");
+  const [serverUrl, setServerUrl] = useState("");
+  const [tools, setTools] = useState<MCPTool[]>([]);
+  const [serverName, setServerName] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [authRequired, setAuthRequired] = useState(false);
+  const [oauthLoading, setOauthLoading] = useState(false);
+  const [showManualToken, setShowManualToken] = useState(false);
+  const [manualToken, setManualToken] = useState("");
+  const [selectedTool, setSelectedTool] = useState<MCPTool | null>(null);
+  const [credentials, setCredentials] = useState<CredentialsMetaInput | null>(
+    null,
+  );
+
+  const oauthLoadingRef = useRef(false);
+  const stateTokenRef = useRef<string | null>(null);
+  const broadcastChannelRef = useRef<BroadcastChannel | null>(null);
+  const messageHandlerRef = useRef<((event: MessageEvent) => void) | null>(
+    null,
+  );
+  const storageHandlerRef = useRef<((event: StorageEvent) => void) | null>(
+    null,
+  );
+  const popupCheckRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const storagePollRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const oauthHandledRef = useRef(false);
+  // (no auto-prefill — dialog starts fresh each time)
+
+  // Clean up listeners on unmount
+  useEffect(() => {
+    return () => {
+      if (messageHandlerRef.current) {
+        window.removeEventListener("message", messageHandlerRef.current);
+      }
+      if (storageHandlerRef.current) {
+        window.removeEventListener("storage", storageHandlerRef.current);
+      }
+      if (broadcastChannelRef.current) {
+        broadcastChannelRef.current.close();
+      }
+      if (popupCheckRef.current) {
+        clearInterval(popupCheckRef.current);
+      }
+      if (storagePollRef.current) {
+        clearInterval(storagePollRef.current);
+      }
+    };
+  }, []);
+
+  const cleanupOAuthListeners = useCallback(() => {
+    if (messageHandlerRef.current) {
+      window.removeEventListener("message", messageHandlerRef.current);
+      messageHandlerRef.current = null;
+    }
+    if (storageHandlerRef.current) {
+      window.removeEventListener("storage", storageHandlerRef.current);
+      storageHandlerRef.current = null;
+    }
+    if (broadcastChannelRef.current) {
+      broadcastChannelRef.current.close();
+      broadcastChannelRef.current = null;
+    }
+    if (popupCheckRef.current) {
+      clearInterval(popupCheckRef.current);
+      popupCheckRef.current = null;
+    }
+    if (storagePollRef.current) {
+      clearInterval(storagePollRef.current);
+      storagePollRef.current = null;
+    }
+    // Clean up any stale localStorage entry
+    try {
+      localStorage.removeItem("mcp_oauth_result");
+    } catch {}
+    setOauthLoading(false);
+    oauthLoadingRef.current = false;
+    // NOTE: do NOT reset oauthHandledRef here — it guards against double-handling
+    // and must only be reset when starting a new OAuth flow.
+  }, []);
+
+  const reset = useCallback(() => {
+    cleanupOAuthListeners();
+    setStep("url");
+    setServerUrl("");
+    setManualToken("");
+    setTools([]);
+    setServerName(null);
+    setLoading(false);
+    setError(null);
+    setAuthRequired(false);
+    setShowManualToken(false);
+    setSelectedTool(null);
+    setCredentials(null);
+    stateTokenRef.current = null;
+  }, [cleanupOAuthListeners]);
+
+  const handleClose = useCallback(() => {
+    reset();
+    onClose();
+  }, [reset, onClose]);
+
+  const discoverTools = useCallback(
+    async (url: string, authToken?: string) => {
+      setLoading(true);
+      setError(null);
+      try {
+        const result = await api.mcpDiscoverTools(url, authToken);
+        setTools(result.tools);
+        setServerName(result.server_name);
+        setAuthRequired(false);
+        setShowManualToken(false);
+        setStep("tool");
+      } catch (e: any) {
+        if (e?.status === 401 || e?.status === 403) {
+          setAuthRequired(true);
+          setError(null);
+        } else {
+          const message =
+            e?.message || e?.detail || "Failed to connect to MCP server";
+          setError(
+            typeof message === "string" ? message : JSON.stringify(message),
+          );
+        }
+      } finally {
+        setLoading(false);
+      }
+    },
+    [api],
+  );
+
+  const handleDiscoverTools = useCallback(() => {
+    if (!serverUrl.trim()) return;
+    discoverTools(serverUrl.trim(), manualToken.trim() || undefined);
+  }, [serverUrl, manualToken, discoverTools]);
+
+  const handleOAuthResult = useCallback(
+    async (data: {
+      success: boolean;
+      code?: string;
+      state?: string;
+      message?: string;
+    }) => {
+      // Prevent double-handling (BroadcastChannel + postMessage may both fire)
+      if (oauthHandledRef.current) return;
+      oauthHandledRef.current = true;
+
+      if (!data.success) {
+        setError(data.message || "OAuth authentication failed.");
+        cleanupOAuthListeners();
+        return;
+      }
+
+      cleanupOAuthListeners();
+      setAuthRequired(false);
+
+      // Exchange code for tokens (stored server-side)
+      setLoading(true);
+      try {
+        const callbackResult = await api.mcpOAuthCallback(
+          data.code!,
+          stateTokenRef.current!,
+        );
+        setCredentials({
+          id: callbackResult.id,
+          provider: callbackResult.provider,
+          type: callbackResult.type,
+          title: callbackResult.title,
+        });
+        const result = await api.mcpDiscoverTools(serverUrl.trim());
+        setTools(result.tools);
+        setServerName(result.server_name);
+        setStep("tool");
+      } catch (e: any) {
+        const status = e?.status;
+        let message: string;
+        if (status === 401 || status === 403) {
+          message =
+            "Authentication succeeded but the server still rejected the request. " +
+            "The token audience may not match. Please try again.";
+        } else {
+          message = e?.message || e?.detail || "Failed to complete sign-in";
+        }
+        setError(
+          typeof message === "string" ? message : JSON.stringify(message),
+        );
+      } finally {
+        setLoading(false);
+      }
+    },
+    [api, serverUrl, cleanupOAuthListeners],
+  );
+
+  const handleOAuthSignIn = useCallback(async () => {
+    if (!serverUrl.trim()) return;
+    setError(null);
+    oauthHandledRef.current = false;
+
+    // Open popup SYNCHRONOUSLY (before async call) to avoid browser popup blockers
+    const width = 500;
+    const height = 700;
+    const left = window.screenX + (window.outerWidth - width) / 2;
+    const top = window.screenY + (window.outerHeight - height) / 2;
+    const popup = window.open(
+      "about:blank",
+      "mcp_oauth",
+      `width=${width},height=${height},left=${left},top=${top},scrollbars=yes`,
+    );
+
+    setOauthLoading(true);
+    oauthLoadingRef.current = true;
+
+    try {
+      const { login_url, state_token } = await api.mcpOAuthLogin(
+        serverUrl.trim(),
+      );
+      stateTokenRef.current = state_token;
+
+      if (popup && !popup.closed) {
+        popup.location.href = login_url;
+      } else {
+        // Popup was blocked — open in new tab as fallback
+        window.open(login_url, "_blank");
+      }
+
+      // Clear any stale localStorage entry before starting
+      try {
+        localStorage.removeItem("mcp_oauth_result");
+      } catch {}
+
+      // Listener 1: BroadcastChannel (works even when window.opener is null)
+      try {
+        const bc = new BroadcastChannel("mcp_oauth");
+        bc.onmessage = (event) => {
+          if (event.data?.type === "mcp_oauth_result") {
+            handleOAuthResult(event.data);
+          }
+        };
+        broadcastChannelRef.current = bc;
+      } catch (e) {
+        console.warn("BroadcastChannel not available:", e);
+      }
+
+      // Listener 2: window.postMessage (fallback)
+      const handleMessage = (event: MessageEvent) => {
+        if (event.origin !== window.location.origin) return;
+        if (event.data?.message_type === "mcp_oauth_result") {
+          handleOAuthResult(event.data);
+        }
+      };
+      messageHandlerRef.current = handleMessage;
+      window.addEventListener("message", handleMessage);
+
+      // Listener 3: localStorage (most reliable cross-tab fallback)
+      const handleStorage = (event: StorageEvent) => {
+        if (event.key === "mcp_oauth_result" && event.newValue) {
+          try {
+            const data = JSON.parse(event.newValue);
+            localStorage.removeItem("mcp_oauth_result");
+            handleOAuthResult(data);
+          } catch {}
+        }
+      };
+      storageHandlerRef.current = handleStorage;
+      window.addEventListener("storage", handleStorage);
+
+      // Fallback 1: Poll localStorage periodically.
+      // StorageEvent only fires in OTHER windows, and BroadcastChannel can fail
+      // in some cross-origin popup scenarios. Direct polling is the most reliable.
+      storagePollRef.current = setInterval(() => {
+        if (!oauthLoadingRef.current || oauthHandledRef.current) {
+          if (storagePollRef.current) clearInterval(storagePollRef.current);
+          return;
+        }
+        try {
+          const stored = localStorage.getItem("mcp_oauth_result");
+          if (stored) {
+            const data = JSON.parse(stored);
+            localStorage.removeItem("mcp_oauth_result");
+            handleOAuthResult(data);
+          }
+        } catch {}
+      }, 500);
+
+      // Fallback 2: detect popup close (gives up if popup closed without result)
+      const popupRef = popup;
+      popupCheckRef.current = setInterval(() => {
+        if (!oauthLoadingRef.current || oauthHandledRef.current) {
+          if (popupCheckRef.current) clearInterval(popupCheckRef.current);
+          return;
+        }
+        if (popupRef && popupRef.closed) {
+          // Grace period: wait one more poll cycle for localStorage to be set
+          setTimeout(() => {
+            if (oauthHandledRef.current) return;
+            try {
+              const stored = localStorage.getItem("mcp_oauth_result");
+              if (stored) {
+                const data = JSON.parse(stored);
+                localStorage.removeItem("mcp_oauth_result");
+                handleOAuthResult(data);
+                return;
+              }
+            } catch {}
+            // Popup closed without result — give up
+            if (popupCheckRef.current) clearInterval(popupCheckRef.current);
+          }, 1000);
+          if (popupCheckRef.current) clearInterval(popupCheckRef.current);
+        }
+      }, 500);
+
+      // Timeout
+      setTimeout(() => {
+        if (oauthLoadingRef.current) {
+          cleanupOAuthListeners();
+          setError("OAuth sign-in timed out. Please try again.");
+        }
+      }, OAUTH_TIMEOUT_MS);
+    } catch (e: any) {
+      if (popup && !popup.closed) popup.close();
+
+      // If server doesn't support OAuth → show manual token entry
+      if (e?.status === 400) {
+        setShowManualToken(true);
+        setError(
+          "This server does not support OAuth sign-in. Please enter a token manually.",
+        );
+      } else {
+        const message = e?.message || "Failed to initiate sign-in";
+        setError(
+          typeof message === "string" ? message : JSON.stringify(message),
+        );
+      }
+      cleanupOAuthListeners();
+    }
+  }, [api, serverUrl, handleOAuthResult, cleanupOAuthListeners]);
+
+  const handleConfirm = useCallback(() => {
+    if (!selectedTool) return;
+
+    const availableTools: Record<string, any> = {};
+    for (const t of tools) {
+      availableTools[t.name] = {
+        description: t.description,
+        input_schema: t.input_schema,
+      };
+    }
+
+    onConfirm({
+      serverUrl: serverUrl.trim(),
+      serverName,
+      selectedTool: selectedTool.name,
+      toolInputSchema: selectedTool.input_schema,
+      availableTools,
+      credentials,
+    });
+    reset();
+  }, [selectedTool, tools, serverUrl, credentials, onConfirm, reset]);
+
+  return (
+    <Dialog open={open} onOpenChange={(isOpen) => !isOpen && handleClose()}>
+      <DialogContent className="max-w-lg">
+        <DialogHeader>
+          <DialogTitle>
+            {step === "url"
+              ? "Connect to MCP Server"
+              : `Select a Tool${serverName ? ` — ${serverName}` : ""}`}
+          </DialogTitle>
+          <DialogDescription>
+            {step === "url"
+              ? "Enter the URL of an MCP server to discover its available tools."
+              : `Found ${tools.length} tool${tools.length !== 1 ? "s" : ""}. Select one to add to your agent.`}
+          </DialogDescription>
+        </DialogHeader>
+
+        {step === "url" && (
+          <div className="flex flex-col gap-4 py-2">
+            <div className="flex flex-col gap-2">
+              <Label htmlFor="mcp-server-url">Server URL</Label>
+              <Input
+                id="mcp-server-url"
+                type="url"
+                placeholder="https://mcp.example.com/mcp"
+                value={serverUrl}
+                onChange={(e) => setServerUrl(e.target.value)}
+                onKeyDown={(e) => e.key === "Enter" && handleDiscoverTools()}
+                autoFocus
+              />
+            </div>
+
+            {/* Auth required: show manual token option */}
+            {authRequired && !showManualToken && (
+              <button
+                onClick={() => setShowManualToken(true)}
+                className="text-xs text-gray-500 underline hover:text-gray-700 dark:text-gray-400 dark:hover:text-gray-300"
+              >
+                or enter a token manually
+              </button>
+            )}
+
+            {/* Manual token entry — only visible when expanded */}
+            {showManualToken && (
+              <div className="flex flex-col gap-2">
+                <Label htmlFor="mcp-auth-token" className="text-sm">
+                  Bearer Token
+                </Label>
+                <Input
+                  id="mcp-auth-token"
+                  type="password"
+                  placeholder="Paste your auth token here"
+                  value={manualToken}
+                  onChange={(e) => setManualToken(e.target.value)}
+                  onKeyDown={(e) => e.key === "Enter" && handleDiscoverTools()}
+                  autoFocus
+                />
+              </div>
+            )}
+
+            {error && <p className="text-sm text-red-500">{error}</p>}
+          </div>
+        )}
+
+        {step === "tool" && (
+          <ScrollArea className="max-h-[50vh] py-2">
+            <div className="flex flex-col gap-2 pr-3">
+              {tools.map((tool) => (
+                <MCPToolCard
+                  key={tool.name}
+                  tool={tool}
+                  selected={selectedTool?.name === tool.name}
+                  onSelect={() => setSelectedTool(tool)}
+                />
+              ))}
+            </div>
+          </ScrollArea>
+        )}
+
+        <DialogFooter>
+          {step === "tool" && (
+            <Button
+              variant="outline"
+              onClick={() => {
+                setStep("url");
+                setSelectedTool(null);
+              }}
+            >
+              Back
+            </Button>
+          )}
+          <Button variant="outline" onClick={handleClose}>
+            Cancel
+          </Button>
+          {step === "url" && (
+            <Button
+              onClick={
+                authRequired && !showManualToken
+                  ? handleOAuthSignIn
+                  : handleDiscoverTools
+              }
+              disabled={!serverUrl.trim() || loading || oauthLoading}
+            >
+              {loading || oauthLoading ? (
+                <span className="flex items-center gap-2">
+                  <LoadingSpinner className="size-4" />
+                  {oauthLoading ? "Waiting for sign-in..." : "Connecting..."}
+                </span>
+              ) : authRequired && !showManualToken ? (
+                "Sign in & Connect"
+              ) : (
+                "Discover Tools"
+              )}
+            </Button>
+          )}
+          {step === "tool" && (
+            <Button onClick={handleConfirm} disabled={!selectedTool}>
+              Add Block
+            </Button>
+          )}
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}
+
+// --------------- Tool Card Component --------------- //
+
+/** Truncate a description to a reasonable length for the collapsed view. */
+function truncateDescription(text: string, maxLen = 120): string {
+  if (text.length <= maxLen) return text;
+  return text.slice(0, maxLen).trimEnd() + "…";
+}
+
+/** Pretty-print a JSON Schema type for a parameter. */
+function schemaTypeLabel(schema: Record<string, any>): string {
+  if (schema.type) return schema.type;
+  if (schema.anyOf)
+    return schema.anyOf.map((s: any) => s.type ?? "any").join(" | ");
+  if (schema.oneOf)
+    return schema.oneOf.map((s: any) => s.type ?? "any").join(" | ");
+  return "any";
+}
+
+function MCPToolCard({
+  tool,
+  selected,
+  onSelect,
+}: {
+  tool: MCPTool;
+  selected: boolean;
+  onSelect: () => void;
+}) {
+  const [expanded, setExpanded] = useState(false);
+  const properties = tool.input_schema?.properties ?? {};
+  const required = new Set<string>(tool.input_schema?.required ?? []);
+  const paramNames = Object.keys(properties);
+
+  // Strip XML-like tags from description for cleaner display.
+  // Loop to handle nested tags like <scr<script>ipt> (CodeQL fix).
+  let cleanDescription = tool.description ?? "";
+  let prev = "";
+  while (prev !== cleanDescription) {
+    prev = cleanDescription;
+    cleanDescription = cleanDescription.replace(/<[^>]*>/g, "");
+  }
+  cleanDescription = cleanDescription.trim();
+
+  return (
+    <button
+      onClick={onSelect}
+      className={`group flex flex-col rounded-lg border text-left transition-colors ${
+        selected
+          ? "border-blue-500 bg-blue-50 dark:border-blue-400 dark:bg-blue-950"
+          : "border-gray-200 hover:border-gray-300 hover:bg-gray-50 dark:border-slate-700 dark:hover:border-slate-600 dark:hover:bg-slate-800"
+      }`}
+    >
+      {/* Header */}
+      <div className="flex items-center gap-2 px-3 pb-1 pt-3">
+        <span className="flex-1 text-sm font-semibold dark:text-white">
+          {tool.name}
+        </span>
+        {paramNames.length > 0 && (
+          <Badge variant="secondary" className="text-[10px]">
+            {paramNames.length} param{paramNames.length !== 1 ? "s" : ""}
+          </Badge>
+        )}
+      </div>
+
+      {/* Description (collapsed: truncated) */}
+      {cleanDescription && (
+        <p className="px-3 pb-1 text-xs leading-relaxed text-gray-500 dark:text-gray-400">
+          {expanded ? cleanDescription : truncateDescription(cleanDescription)}
+        </p>
+      )}
+
+      {/* Parameter badges (collapsed view) */}
+      {!expanded && paramNames.length > 0 && (
+        <div className="flex flex-wrap gap-1 px-3 pb-2">
+          {paramNames.slice(0, 6).map((name) => (
+            <Badge
+              key={name}
+              variant="outline"
+              className="text-[10px] font-normal"
+            >
+              {name}
+              {required.has(name) && (
+                <span className="ml-0.5 text-red-400">*</span>
+              )}
+            </Badge>
+          ))}
+          {paramNames.length > 6 && (
+            <Badge variant="outline" className="text-[10px] font-normal">
+              +{paramNames.length - 6} more
+            </Badge>
+          )}
+        </div>
+      )}
+
+      {/* Expanded: full parameter details */}
+      {expanded && paramNames.length > 0 && (
+        <div className="mx-3 mb-2 rounded border border-gray-100 bg-gray-50/50 dark:border-slate-700 dark:bg-slate-800/50">
+          <table className="w-full text-xs">
+            <thead>
+              <tr className="border-b border-gray-100 dark:border-slate-700">
+                <th className="px-2 py-1 text-left font-medium text-gray-500 dark:text-gray-400">
+                  Parameter
+                </th>
+                <th className="px-2 py-1 text-left font-medium text-gray-500 dark:text-gray-400">
+                  Type
+                </th>
+                <th className="px-2 py-1 text-left font-medium text-gray-500 dark:text-gray-400">
+                  Description
+                </th>
+              </tr>
+            </thead>
+            <tbody>
+              {paramNames.map((name) => {
+                const prop = properties[name] ?? {};
+                return (
+                  <tr
+                    key={name}
+                    className="border-b border-gray-50 last:border-0 dark:border-slate-700/50"
+                  >
+                    <td className="px-2 py-1 font-mono text-[11px] text-gray-700 dark:text-gray-300">
+                      {name}
+                      {required.has(name) && (
+                        <span className="ml-0.5 text-red-400">*</span>
+                      )}
+                    </td>
+                    <td className="px-2 py-1 text-gray-500 dark:text-gray-400">
+                      {schemaTypeLabel(prop)}
+                    </td>
+                    <td className="max-w-[200px] truncate px-2 py-1 text-gray-500 dark:text-gray-400">
+                      {prop.description ?? "—"}
+                    </td>
+                  </tr>
+                );
+              })}
+            </tbody>
+          </table>
+        </div>
+      )}
+
+      {/* Toggle details */}
+      {(paramNames.length > 0 || cleanDescription.length > 120) && (
+        <button
+          type="button"
+          onClick={(e) => {
+            e.stopPropagation();
+            setExpanded((prev) => !prev);
+          }}
+          className="flex w-full items-center justify-center gap-1 border-t border-gray-100 py-1.5 text-[10px] text-gray-400 hover:text-gray-600 dark:border-slate-700 dark:text-gray-500 dark:hover:text-gray-300"
+        >
+          {expanded ? "Hide details" : "Show details"}
+          <CaretDown
+            className={`h-3 w-3 transition-transform ${expanded ? "rotate-180" : ""}`}
+          />
+        </button>
+      )}
+    </button>
+  );
+}

autogpt_platform/frontend/src/app/api/openapi.json

@@ -4237,6 +4237,128 @@
         }
       }
     },
+    "/api/mcp/discover-tools": {
+      "post": {
+        "tags": ["v2", "mcp", "mcp"],
+        "summary": "Discover available tools on an MCP server",
+        "description": "Connect to an MCP server and return its available tools.\n\nIf the user has a stored MCP credential for this server URL, it will be\nused automatically — no need to pass an explicit auth token.",
+        "operationId": "postV2Discover available tools on an mcp server",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/DiscoverToolsRequest" }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/DiscoverToolsResponse"
+                }
+              }
+            }
+          },
+          "401": {
+            "$ref": "#/components/responses/HTTP401NotAuthenticatedError"
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/HTTPValidationError" }
+              }
+            }
+          }
+        },
+        "security": [{ "HTTPBearerJWT": [] }]
+      }
+    },
+    "/api/mcp/oauth/callback": {
+      "post": {
+        "tags": ["v2", "mcp", "mcp"],
+        "summary": "Exchange OAuth code for MCP tokens",
+        "description": "Exchange the authorization code for tokens and store the credential.\n\nThe frontend calls this after receiving the OAuth code from the popup.\nOn success, subsequent ``/discover-tools`` calls for the same server URL\nwill automatically use the stored credential.",
+        "operationId": "postV2Exchange oauth code for mcp tokens",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/MCPOAuthCallbackRequest"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/CredentialsMetaResponse"
+                }
+              }
+            }
+          },
+          "401": {
+            "$ref": "#/components/responses/HTTP401NotAuthenticatedError"
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/HTTPValidationError" }
+              }
+            }
+          }
+        },
+        "security": [{ "HTTPBearerJWT": [] }]
+      }
+    },
+    "/api/mcp/oauth/login": {
+      "post": {
+        "tags": ["v2", "mcp", "mcp"],
+        "summary": "Initiate OAuth login for an MCP server",
+        "description": "Discover OAuth metadata from the MCP server and return a login URL.\n\n1. Discovers the protected-resource metadata (RFC 9728)\n2. Fetches the authorization server metadata (RFC 8414)\n3. Performs Dynamic Client Registration (RFC 7591) if available\n4. Returns the authorization URL for the frontend to open in a popup",
+        "operationId": "postV2Initiate oauth login for an mcp server",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/MCPOAuthLoginRequest" }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/MCPOAuthLoginResponse"
+                }
+              }
+            }
+          },
+          "401": {
+            "$ref": "#/components/responses/HTTP401NotAuthenticatedError"
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/HTTPValidationError" }
+              }
+            }
+          }
+        },
+        "security": [{ "HTTPBearerJWT": [] }]
+      }
+    },
     "/api/oauth/app/{client_id}": {
       "get": {
         "tags": ["oauth"],
@@ -7175,7 +7297,7 @@
           "host": {
             "anyOf": [{ "type": "string" }, { "type": "null" }],
             "title": "Host",
-            "description": "Host pattern for host-scoped credentials"
+            "description": "Host pattern for host-scoped or MCP server URL for MCP credentials"
           }
         },
         "type": "object",
@@ -7195,6 +7317,45 @@
         "required": ["version_counts"],
         "title": "DeleteGraphResponse"
       },
+      "DiscoverToolsRequest": {
+        "properties": {
+          "server_url": {
+            "type": "string",
+            "title": "Server Url",
+            "description": "URL of the MCP server"
+          },
+          "auth_token": {
+            "anyOf": [{ "type": "string" }, { "type": "null" }],
+            "title": "Auth Token",
+            "description": "Optional Bearer token for authenticated MCP servers"
+          }
+        },
+        "type": "object",
+        "required": ["server_url"],
+        "title": "DiscoverToolsRequest",
+        "description": "Request to discover tools on an MCP server."
+      },
+      "DiscoverToolsResponse": {
+        "properties": {
+          "tools": {
+            "items": { "$ref": "#/components/schemas/MCPToolResponse" },
+            "type": "array",
+            "title": "Tools"
+          },
+          "server_name": {
+            "anyOf": [{ "type": "string" }, { "type": "null" }],
+            "title": "Server Name"
+          },
+          "protocol_version": {
+            "anyOf": [{ "type": "string" }, { "type": "null" }],
+            "title": "Protocol Version"
+          }
+        },
+        "type": "object",
+        "required": ["tools"],
+        "title": "DiscoverToolsResponse",
+        "description": "Response containing the list of tools available on an MCP server."
+      },
       "Document": {
         "properties": {
           "url": { "type": "string", "title": "Url" },
@@ -8562,6 +8723,62 @@
         "required": ["login_url", "state_token"],
         "title": "LoginResponse"
       },
+      "MCPOAuthCallbackRequest": {
+        "properties": {
+          "code": {
+            "type": "string",
+            "title": "Code",
+            "description": "Authorization code from OAuth callback"
+          },
+          "state_token": {
+            "type": "string",
+            "title": "State Token",
+            "description": "State token for CSRF verification"
+          }
+        },
+        "type": "object",
+        "required": ["code", "state_token"],
+        "title": "MCPOAuthCallbackRequest",
+        "description": "Request to exchange an OAuth code for tokens."
+      },
+      "MCPOAuthLoginRequest": {
+        "properties": {
+          "server_url": {
+            "type": "string",
+            "title": "Server Url",
+            "description": "URL of the MCP server that requires OAuth"
+          }
+        },
+        "type": "object",
+        "required": ["server_url"],
+        "title": "MCPOAuthLoginRequest",
+        "description": "Request to start an OAuth flow for an MCP server."
+      },
+      "MCPOAuthLoginResponse": {
+        "properties": {
+          "login_url": { "type": "string", "title": "Login Url" },
+          "state_token": { "type": "string", "title": "State Token" }
+        },
+        "type": "object",
+        "required": ["login_url", "state_token"],
+        "title": "MCPOAuthLoginResponse",
+        "description": "Response with the OAuth login URL for the user to authenticate."
+      },
+      "MCPToolResponse": {
+        "properties": {
+          "name": { "type": "string", "title": "Name" },
+          "description": { "type": "string", "title": "Description" },
+          "input_schema": {
+            "additionalProperties": true,
+            "type": "object",
+            "title": "Input Schema"
+          }
+        },
+        "type": "object",
+        "required": ["name", "description", "input_schema"],
+        "title": "MCPToolResponse",
+        "description": "A single MCP tool returned by discovery."
+      },
       "MarketplaceListing": {
         "properties": {
           "id": { "type": "string", "title": "Id" },

autogpt_platform/frontend/src/components/contextual/CredentialsInput/CredentialsInput.tsx

@@ -86,7 +86,8 @@ export function CredentialsInput({
     handleCredentialSelect,
   } = hookData;
 
-  const displayName = toDisplayName(provider);
+  const displayName =
+    (schema as any).display_name || toDisplayName(provider);
   const selectedCredentialIsSystem =
     selectedCredential && isSystemCredential(selectedCredential);
 

autogpt_platform/frontend/src/components/contextual/CredentialsInput/useCredentialsInput.ts

@@ -149,6 +149,7 @@ export function useCredentialsInput({
     savedCredentials,
     oAuthCallback,
     isSystemProvider,
+    discriminatorValue,
   } = credentials;
 
   // Split credentials into user and system
@@ -157,10 +158,23 @@ export function useCredentialsInput({
 
   async function handleOAuthLogin() {
     setOAuthError(null);
-    const { login_url, state_token } = await api.oAuthLogin(
+
-      provider,
+    // MCP uses dynamic OAuth discovery per server URL
-      schema.credentials_scopes,
+    const isMCP = provider === "mcp" && !!discriminatorValue;
-    );
+    let login_url: string;
+    let state_token: string;
+
+    if (isMCP) {
+      ({ login_url, state_token } = await api.mcpOAuthLogin(
+        discriminatorValue!,
+      ));
+    } else {
+      ({ login_url, state_token } = await api.oAuthLogin(
+        provider,
+        schema.credentials_scopes,
+      ));
+    }
+
     setOAuth2FlowInProgress(true);
     const popup = window.open(login_url, "_blank", "popup=true");
 
@@ -205,29 +219,34 @@ export function useCredentialsInput({
 
       try {
         console.debug("Processing OAuth callback");
-        const credentials = await oAuthCallback(e.data.code, e.data.state);
+        // MCP uses its own callback endpoint
+        const credentials = isMCP
+          ? await api.mcpOAuthCallback(e.data.code, e.data.state)
+          : await oAuthCallback(e.data.code, e.data.state);
         console.debug("OAuth callback processed successfully");
 
-        // Check if the credential's scopes match the required scopes
+        // Check if the credential's scopes match the required scopes (skip for MCP)
-        const requiredScopes = schema.credentials_scopes;
+        if (!isMCP) {
-        if (requiredScopes && requiredScopes.length > 0) {
+          const requiredScopes = schema.credentials_scopes;
-          const grantedScopes = new Set(credentials.scopes || []);
+          if (requiredScopes && requiredScopes.length > 0) {
-          const hasAllRequiredScopes = new Set(requiredScopes).isSubsetOf(
+            const grantedScopes = new Set(credentials.scopes || []);
-            grantedScopes,
+            const hasAllRequiredScopes = new Set(requiredScopes).isSubsetOf(
-          );
+              grantedScopes,
+            );
 
-          if (!hasAllRequiredScopes) {
+            if (!hasAllRequiredScopes) {
-            console.error(
+              console.error(
-              `Newly created OAuth credential for ${providerName} has insufficient scopes. Required:`,
+                `Newly created OAuth credential for ${providerName} has insufficient scopes. Required:`,
-              requiredScopes,
+                requiredScopes,
-              "Granted:",
+                "Granted:",
-              credentials.scopes,
+                credentials.scopes,
-            );
+              );
-            setOAuthError(
+              setOAuthError(
-              "Connection failed: the granted permissions don't match what's required. " +
+                "Connection failed: the granted permissions don't match what's required. " +
-                "Please contact the application administrator.",
+                  "Please contact the application administrator.",
-            );
+              );
-            return;
+              return;
+            }
           }
         }
 

autogpt_platform/frontend/src/hooks/useCredentials.ts

@@ -100,6 +100,11 @@ export default function useCredentials(
       return false;
     }
 
+    // Filter MCP OAuth2 credentials by server URL matching
+    if (c.type === "oauth2" && c.provider === "mcp") {
+      return discriminatorValue != null && c.host === discriminatorValue;
+    }
+
     // Filter by OAuth credentials that have sufficient scopes for this block
     if (c.type === "oauth2") {
       const requiredScopes = credsInputSchema.credentials_scopes;

autogpt_platform/frontend/src/lib/autogpt-server-api/client.ts

@@ -33,6 +33,7 @@ import type {
   GraphMeta,
   GraphUpdateable,
   HostScopedCredentials,
+  MCPDiscoverToolsResponse,
   LibraryAgent,
   LibraryAgentID,
   LibraryAgentPreset,
@@ -792,6 +793,38 @@ export default class BackendAPI {
     return this._request("POST", "/otto/ask", query);
   }
 
+  ////////////////////////////////////////
+  ///////////// MCP FUNCTIONS ////////////
+  ////////////////////////////////////////
+
+  async mcpDiscoverTools(
+    serverUrl: string,
+    authToken?: string,
+  ): Promise<MCPDiscoverToolsResponse> {
+    return this._request("POST", "/mcp/discover-tools", {
+      server_url: serverUrl,
+      auth_token: authToken || null,
+    });
+  }
+
+  async mcpOAuthLogin(
+    serverUrl: string,
+  ): Promise<{ login_url: string; state_token: string }> {
+    return this._request("POST", "/mcp/oauth/login", {
+      server_url: serverUrl,
+    });
+  }
+
+  async mcpOAuthCallback(
+    code: string,
+    stateToken: string,
+  ): Promise<CredentialsMetaResponse> {
+    return this._request("POST", "/mcp/oauth/callback", {
+      code,
+      state_token: stateToken,
+    });
+  }
+
   ////////////////////////////////////////
   ////////// INTERNAL FUNCTIONS //////////
   ////////////////////////////////////////

autogpt_platform/frontend/src/lib/autogpt-server-api/types.ts

@@ -753,10 +753,23 @@ export enum BlockUIType {
 
 export enum SpecialBlockID {
   AGENT = "e189baac-8c20-45a1-94a7-55177ea42565",
+  MCP_TOOL = "a0a4b1c2-d3e4-4f56-a7b8-c9d0e1f2a3b4",
   SMART_DECISION = "3b191d9f-356f-482d-8238-ba04b6d18381",
   OUTPUT = "363ae599-353e-4804-937e-b2ee3cef3da4",
 }
 
+export type MCPTool = {
+  name: string;
+  description: string;
+  input_schema: Record<string, any>;
+};
+
+export type MCPDiscoverToolsResponse = {
+  tools: MCPTool[];
+  server_name: string | null;
+  protocol_version: string | null;
+};
+
 export type AnalyticsMetrics = {
   metric_name: string;
   metric_value: number;

autogpt_platform/frontend/src/middleware.ts

@@ -18,6 +18,6 @@ export const config = {
      * Note: /auth/authorize and /auth/integrations/* ARE protected and need
      * middleware to run for authentication checks.
      */
-    "/((?!_next/static|_next/image|favicon.ico|auth/callback|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)",
+    "/((?!_next/static|_next/image|favicon.ico|auth/callback|auth/integrations/mcp_callback|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)",
   ],
 };

docs/integrations/README.md

@@ -467,6 +467,7 @@ Below is a comprehensive list of all available blocks, categorized by their prim
 | [Github Update Comment](block-integrations/github/issues.md#github-update-comment) | A block that updates an existing comment on a GitHub issue or pull request |
 | [Github Update File](block-integrations/github/repo.md#github-update-file) | This block updates an existing file in a GitHub repository |
 | [Instantiate Code Sandbox](block-integrations/misc.md#instantiate-code-sandbox) | Instantiate a sandbox environment with internet access in which you can execute code with the Execute Code Step block |
+| [MCP Tool](block-integrations/mcp/block.md#mcp-tool) | Connect to any MCP server and execute its tools |
 | [Slant3D Order Webhook](block-integrations/slant3d/webhook.md#slant3d-order-webhook) | This block triggers on Slant3D order status updates and outputs the event details, including tracking information when orders are shipped |
 
 ## Media Generation

docs/integrations/SUMMARY.md

@@ -84,6 +84,7 @@
 * [Linear Projects](block-integrations/linear/projects.md)
 * [LLM](block-integrations/llm.md)
 * [Logic](block-integrations/logic.md)
+* [Mcp Block](block-integrations/mcp/block.md)
 * [Misc](block-integrations/misc.md)
 * [Notion Create Page](block-integrations/notion/create_page.md)
 * [Notion Read Database](block-integrations/notion/read_database.md)

docs/integrations/block-integrations/mcp/block.md

@@ -0,0 +1,36 @@
+# Mcp Block
+<!-- MANUAL: file_description -->
+_Add a description of this category of blocks._
+<!-- END MANUAL -->
+
+## MCP Tool
+
+### What it is
+Connect to any MCP server and execute its tools. Provide a server URL, select a tool, and pass arguments dynamically.
+
+### How it works
+<!-- MANUAL: how_it_works -->
+_Add technical explanation here._
+<!-- END MANUAL -->
+
+### Inputs
+
+| Input | Description | Type | Required |
+|-------|-------------|------|----------|
+| server_url | URL of the MCP server (Streamable HTTP endpoint) | str | Yes |
+| selected_tool | The MCP tool to execute | str | No |
+| tool_arguments | Arguments to pass to the selected MCP tool. The fields here are defined by the tool's input schema. | Dict[str, Any] | No |
+
+### Outputs
+
+| Output | Description | Type |
+|--------|-------------|------|
+| error | Error message if the tool call failed | str |
+| result | The result returned by the MCP tool | Result |
+
+### Possible use case
+<!-- MANUAL: use_case -->
+_Add practical use case examples here._
+<!-- END MANUAL -->
+
+---