fix(mcp): Remove silent exception swallowing in credential lookup

Let credential lookup errors propagate in discover_tools endpoint
instead of silently catching all exceptions. Upgrade block.py
auto-lookup logging from debug to warning. Update tests to mock
creds_manager so they don't hit the database.

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

@@ -78,32 +78,29 @@ async def discover_tools(
 
     # 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, ProviderName.MCP.value
-            )
-            # 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
+        mcp_creds = await creds_manager.store.get_creds_by_provider(
+            user_id, ProviderName.MCP.value
+        )
+        # 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)
                 ):
-                    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:
-                # Refresh the token if expired before using it
-                best_cred = await creds_manager.refresh_if_needed(user_id, 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)
+                    best_cred = cred
+        if best_cred:
+            # Refresh the token if expired before using it
+            best_cred = await creds_manager.refresh_if_needed(user_id, 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()
 
     client = MCPClient(request.server_url, auth_token=auth_token)
 

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

@@ -54,7 +54,11 @@ class TestDiscoverTools:
             ),
         ]
 
-        with (patch("backend.api.features.mcp.routes.MCPClient") as MockClient,):
+        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=[])
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 return_value={
@@ -143,7 +147,11 @@ class TestDiscoverTools:
 
     @pytest.mark.asyncio(loop_scope="session")
     async def test_discover_tools_mcp_error(self, client):
-        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+        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=[])
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=MCPClientError("Connection refused")
@@ -159,7 +167,11 @@ class TestDiscoverTools:
 
     @pytest.mark.asyncio(loop_scope="session")
     async def test_discover_tools_generic_error(self, client):
-        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+        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=[])
             instance = MockClient.return_value
             instance.initialize = AsyncMock(side_effect=Exception("Network timeout"))
 
@@ -173,7 +185,11 @@ class TestDiscoverTools:
 
     @pytest.mark.asyncio(loop_scope="session")
     async def test_discover_tools_auth_required(self, client):
-        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+        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=[])
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=HTTPClientError("HTTP 401 Error: Unauthorized", 401)
@@ -189,7 +205,11 @@ class TestDiscoverTools:
 
     @pytest.mark.asyncio(loop_scope="session")
     async def test_discover_tools_forbidden(self, client):
-        with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
+        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=[])
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=HTTPClientError("HTTP 403 Error: Forbidden", 403)

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

@@ -241,7 +241,7 @@ class MCPToolBlock(Block):
                 )
             return best
         except Exception:
-            logger.debug("Auto-lookup MCP credential failed", exc_info=True)
+            logger.warning("Auto-lookup MCP credential failed", exc_info=True)
             return None
 
     async def run(