feat: adding support for Model Context Protocol (MCP). (#396)

Adding Toolbox support for MCP. Toolbox can now be run as an MCP server. Fixes #312. --------- Co-authored-by: Jack Wotherspoon <jackwoth@google.com> Co-authored-by: Kurtis Van Gent <31518063+kurtisvg@users.noreply.github.com> Co-authored-by: Averi Kitsch <akitsch@google.com>
2026-01-09 15:38:08 -05:00 · 2025-04-04 11:24:34 -07:00
parent 55dff38db2
commit a7d1d4eb2a
36 changed files with 1833 additions and 61 deletions
--- a/docs/en/about/faq.md
+++ b/docs/en/about/faq.md
@@ -80,9 +80,5 @@ with clients in their preferred language. As Gen AI matures, we want developers

 ## Is Toolbox compatible with Model Context Protocol (MCP)? 

-Toolbox currently uses it's own custom protocol for server-client communication.
-[Anthropic's Model Context Protocol (MCP)](https://modelcontextprotocol.io/)
-launched towards the end of Toolbox's development, and is currently missing
-functionality to support some of our features. We're currently exploring how
-best to bring Toolbox's functionality to the wider MCP ecosystem.
-
+Yes! Toolbox is compatible with [Anthropic's Model Context Protocol (MCP)](https://modelcontextprotocol.io/). Please checkout [Connect via MCP](../how-to/connect_via_mcp.md) on how to
+connect to Toolbox with an MCP client.
--- a/docs/en/concepts/telemetry/index.md
+++ b/docs/en/concepts/telemetry/index.md
@@ -81,18 +81,22 @@ A metric is a measurement of a service captured at runtime. The collected data
 can be used to provide important insights into the service. Toolbox provides the
 following custom metrics:

-| **Metric Name**                    | **Description**                                       |
-|------------------------------------|-------------------------------------------------------|
-| `toolbox.server.toolset.get.count` | Counts the number of toolset manifest requests served |
-| `toolbox.server.tool.get.count`    | Counts the number of tool manifest requests served    |
-| `toolbox.server.tool.get.invoke`   | Counts the number of tool invocation requests served  |
+| **Metric Name**                    | **Description**                                         |
+|------------------------------------|---------------------------------------------------------|
+| `toolbox.server.toolset.get.count` | Counts the number of toolset manifest requests served   |
+| `toolbox.server.tool.get.count`    | Counts the number of tool manifest requests served      |
+| `toolbox.server.tool.get.invoke`   | Counts the number of tool invocation requests served    |
+| `toolbox.server.mcp.sse.count`     | Counts the number of mcp sse connection requests served |
+| `toolbox.server.mcp.post.count`    | Counts the number of mcp post requests served           |

 All custom metrics have the following attributes/labels:

-| **Metric Attributes** | **Description**                                           |
-|-----------------------|-----------------------------------------------------------|
-| `toolbox.name`        | Name of the toolset or tool, if applicable.               |
-| `toolbox.status`      | Operation status code, for example: `success`, `failure`. |
+| **Metric Attributes**      | **Description**                                           |
+|----------------------------|-----------------------------------------------------------|
+| `toolbox.name`             | Name of the toolset or tool, if applicable.               |
+| `toolbox.operation.status` | Operation status code, for example: `success`, `failure`. |
+| `toolbox.sse.sessionId`    | Session id for sse connection, if applicable.             |
+| `toolbox.method`           | Method of JSON-RPC request, if applicable.                |

 ### Traces

--- a/docs/en/getting-started/configure.md
+++ b/docs/en/getting-started/configure.md
@@ -1,7 +1,7 @@
 ---
 title: "Configuration"
 type: docs
-weight: 3
+weight: 4
 description: How to configure Toolbox's tools.yaml file.
 ---

--- a/docs/en/getting-started/local_quickstart.md
+++ b/docs/en/getting-started/local_quickstart.md
@@ -1,5 +1,5 @@
 ---
-title: "Quickstart"
+title: "Quickstart (Local)"
 type: docs
 weight: 2
 description: >
--- a/docs/en/getting-started/mcp_quickstart/_index.md
+++ b/docs/en/getting-started/mcp_quickstart/_index.md
@@ -0,0 +1,228 @@
+---
+title: "Quickstart (MCP)"
+type: docs
+weight: 3
+description: >
+  How to get started running Toolbox locally with MCP Inspector. 
+---
+
+## Overview
+[Model Context Protocol](https://modelcontextprotocol.io) is an open protocol
+that standardizes how applications provide context to LLMs. Check out this page
+on how to [connect to Toolbox via MCP](../../how-to/connect_via_mcp.md).
+
+## Step 1: Set up your database
+
+In this section, we will create a database, insert some data that needs to be
+access by our agent, and create a database user for Toolbox to connect with. 
+
+1. Connect to postgres using the `psql` command:
+
+    ```bash
+    psql -h 127.0.0.1 -U postgres
+    ```
+
+    Here, `postgres` denotes the default postgres superuser.
+
+1. Create a new database and a new user:
+
+    {{< notice tip >}} 
+  For a real application, it's best to follow the principle of least permission 
+  and only grant the privileges your application needs. 
+    {{< /notice >}}
+
+    ```sql
+      CREATE USER toolbox_user WITH PASSWORD 'my-password';
+
+      CREATE DATABASE toolbox_db;
+      GRANT ALL PRIVILEGES ON DATABASE toolbox_db TO toolbox_user;
+
+      ALTER DATABASE toolbox_db OWNER TO toolbox_user;
+    ```
+
+
+
+1. End the database session:
+
+    ```bash
+    \q
+    ```
+
+1. Connect to your database with your new user:
+
+    ```bash
+    psql -h 127.0.0.1 -U toolbox_user -d toolbox_db
+    ```
+
+1. Create a table using the following command:
+
+    ```sql
+    CREATE TABLE hotels(
+      id            INTEGER NOT NULL PRIMARY KEY,
+      name          VARCHAR NOT NULL,
+      location      VARCHAR NOT NULL,
+      price_tier    VARCHAR NOT NULL,
+      checkin_date  DATE    NOT NULL,
+      checkout_date DATE    NOT NULL,
+      booked        BIT     NOT NULL
+    );
+    ```
+
+1. Insert data into the table.
+
+    ```sql
+    INSERT INTO hotels(id, name, location, price_tier, checkin_date, checkout_date, booked)
+    VALUES 
+      (1, 'Hilton Basel', 'Basel', 'Luxury', '2024-04-22', '2024-04-20', B'0'),
+      (2, 'Marriott Zurich', 'Zurich', 'Upscale', '2024-04-14', '2024-04-21', B'0'),
+      (3, 'Hyatt Regency Basel', 'Basel', 'Upper Upscale', '2024-04-02', '2024-04-20', B'0'),
+      (4, 'Radisson Blu Lucerne', 'Lucerne', 'Midscale', '2024-04-24', '2024-04-05', B'0'),
+      (5, 'Best Western Bern', 'Bern', 'Upper Midscale', '2024-04-23', '2024-04-01', B'0'),
+      (6, 'InterContinental Geneva', 'Geneva', 'Luxury', '2024-04-23', '2024-04-28', B'0'),
+      (7, 'Sheraton Zurich', 'Zurich', 'Upper Upscale', '2024-04-27', '2024-04-02', B'0'),
+      (8, 'Holiday Inn Basel', 'Basel', 'Upper Midscale', '2024-04-24', '2024-04-09', B'0'),
+      (9, 'Courtyard Zurich', 'Zurich', 'Upscale', '2024-04-03', '2024-04-13', B'0'),
+      (10, 'Comfort Inn Bern', 'Bern', 'Midscale', '2024-04-04', '2024-04-16', B'0');
+    ```
+
+1. End the database session:
+
+    ```bash
+    \q
+    ```
+
+## Step 2: Install and configure Toolbox
+
+In this section, we will download Toolbox, configure our tools in a
+`tools.yaml`, and then run the Toolbox server.
+
+1. Download the latest version of Toolbox as a binary:
+
+    {{< notice tip >}} 
+  Select the 
+  [correct binary](https://github.com/googleapis/genai-toolbox/releases) 
+  corresponding to your OS and CPU architecture. 
+    {{< /notice >}}
+    <!-- {x-release-please-start-version} -->
+    ```bash
+    export OS="linux/amd64" # one of linux/amd64, darwin/arm64, darwin/amd64, or windows/amd64
+    curl -O https://storage.googleapis.com/genai-toolbox/v0.2.1/$OS/toolbox
+    ```
+    <!-- {x-release-please-end} -->
+
+1. Make the binary executable:
+
+    ```bash
+    chmod +x toolbox
+    ```
+
+1. Write the following into a `tools.yaml` file. Be sure to update any fields
+   such as `user`, `password`, or `database` that you may have customized in the
+   previous step.
+
+    ```yaml
+    sources:
+      my-pg-source:
+        kind: postgres
+        host: 127.0.0.1
+        port: 5432
+        database: toolbox_db
+        user: toolbox_user
+        password: my-password
+    tools:
+      search-hotels-by-name:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Search for hotels based on name.
+        parameters:
+          - name: name
+            type: string
+            description: The name of the hotel.
+        statement: SELECT * FROM hotels WHERE name ILIKE '%' || $1 || '%';
+      search-hotels-by-location:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Search for hotels based on location.
+        parameters:
+          - name: location
+            type: string
+            description: The location of the hotel.
+        statement: SELECT * FROM hotels WHERE location ILIKE '%' || $1 || '%';
+      book-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: >-
+           Book a hotel by its ID. If the hotel is successfully booked, returns a NULL, raises an error if not.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to book.
+        statement: UPDATE hotels SET booked = B'1' WHERE id = $1;
+      update-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: >-
+          Update a hotel's check-in and check-out dates by its ID. Returns a message
+          indicating  whether the hotel was successfully updated or not.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to update.
+          - name: checkin_date
+            type: string
+            description: The new check-in date of the hotel.
+          - name: checkout_date
+            type: string
+            description: The new check-out date of the hotel.
+        statement: >-
+          UPDATE hotels SET checkin_date = CAST($2 as date), checkout_date = CAST($3
+          as date) WHERE id = $1;
+      cancel-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Cancel a hotel by its ID.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to cancel.
+        statement: UPDATE hotels SET booked = B'0' WHERE id = $1;
+    ```
+    For more info on tools, check out the `Resources` section of the docs.
+
+1. Run the Toolbox server, pointing to the `tools.yaml` file created earlier:
+
+    ```bash
+    ./toolbox --tools_file "tools.yaml"
+    ```
+
+## Step 3: Connect to MCP Inspector
+
+1. Run the MCP Inspector:
+
+    ```bash
+    npx @modelcontextprotocol/inspector
+    ```
+
+1. Type `y` when it asks to install the inspector package.
+
+1. It should show the folo=lowing when the MCP Inspector is up and runnning:
+
+    ```bash
+    🔍 MCP Inspector is up and running at http://127.0.0.1:5173 🚀
+    ```
+
+1. Open the above link in your browser.
+
+1. For `Transport Type`, select `SSE`.
+
+1. For `URL`, type in `http://127.0.0.1:5000/mcp/sse`.
+
+1. Click Connect.
+
+    ![inspector](./inspector.png)
+
+1. Select `List Tools`, you will see a list of tools configured in `tools.yaml`.
+
+    ![inspector_tools](./inspector_tools.png)
+
+1. Test out your tools here!
--- a/docs/en/getting-started/mcp_quickstart/inspector.png
+++ b/docs/en/getting-started/mcp_quickstart/inspector.png
--- a/docs/en/getting-started/mcp_quickstart/inspector_tools.png
+++ b/docs/en/getting-started/mcp_quickstart/inspector_tools.png
--- a/docs/en/how-to/connect_via_mcp.md
+++ b/docs/en/how-to/connect_via_mcp.md
@@ -0,0 +1,76 @@
+---
+title: "Connect via MCP Client"
+type: docs
+weight: 1
+description: >
+  How to connect to Toolbox from a MCP Client.
+---
+
+## Toolbox SDKs vs Model Context Protocol (MCP)
+Toolbox now supports connections via both the native Toolbox SDKs and via [Model Context Protocol (MCP)](https://modelcontextprotocol.io/). However, Toolbox as several features which are not supported in the MCP specification (such as Authenticated Parameters and Authorized invocation). 
+
+We recommend using the native SDKs over MCP clients to leverage these features. The native SDKs can be combined with MCP clients in many cases. 
+
+### Protocol Versions
+Toolbox currently supports the following versions of MCP specification:
+* [2024-11-05](https://spec.modelcontextprotocol.io/specification/2024-11-05/)
+
+### Features Not Supported by MCP
+Toolbox has several features that are not yet supported in the MCP specification:
+* **AuthZ/AuthN:** There are no auth implementation in the `2024-11-05` specification. This includes:
+  * [Authenticated Parameters](../resources/tools/_index.md#authenticated-parameters)
+  * [Authorized Invocations](../resources/tools/_index.md#authorized-invocations)
+* **Toolsets**: MCP does not have the concept of toolset. Hence, all tools are automatically loaded when using Toolbox with MCP.
+* **Notifications:** Currently, editing Toolbox Tools requires a server restart. Clients should reload tools on disconnect to get the latest version. 
+
+
+## Connecting to Toolbox with an MCP client
+### Before you begin
+
+{{< notice note >}} 
+MCP is only compatible with Toolbox version 0.3.0 and above.
+{{< /notice >}}
+
+1. [Install](../getting-started/introduction/_index.md#installing-the-server) Toolbox version 0.3.0+.
+
+1. Make sure you've set up and initialized your database.
+
+1. [Set up](../getting-started/configure.md) your `tools.yaml` file.
+
+### Connecting via HTTP
+Toolbox supports the HTTP transport protocol with and without SSE.
+
+{{< tabpane text=true >}} {{% tab header="HTTP with SSE" lang="en" %}}
+Add the following configuration to your MCP client configuration:
+```bash
+{
+  "mcpServers": {
+    "toolbox": {
+      "type": "sse",
+      "url": "http://127.0.0.1:5000/mcp/sse",
+    }
+  }
+}
+```
+{{% /tab %}} {{% tab header="HTTP POST" lang="en" %}}
+Connect to Toolbox HTTP POST via `http://127.0.0.1:5000/mcp`.
+{{% /tab %}} {{< /tabpane >}}
+
+### Using the MCP Inspector with Toolbox
+
+Use MCP [Inspector](https://github.com/modelcontextprotocol/inspector) for testing and debugging Toolbox server.
+
+1. [Run Toolbox](../getting-started/introduction/_index.md#running-the-server).
+
+1. In a separate terminal, run Inspector directly through `npx`:
+
+    ```bash
+    npx @modelcontextprotocol/inspector
+    ```
+
+1. For `Transport Type` dropdown menu, select `SSE`.
+
+1. For `URL`, type in `http://127.0.0.1:5000/mcp/sse`.
+
+1. Click the `Connect` button. Voila! You should be able to inspect your toolbox
+   tools!
--- a/internal/server/api_test.go
+++ b/internal/server/api_test.go
@@ -24,8 +24,9 @@ import (
 )

 func TestToolsetEndpoint(t *testing.T) {
-	toolsMap, toolsets := setUpResources(t)
-	ts, shutdown := setUpServer(t, toolsMap, toolsets)
+	mockTools := []MockTool{tool1, tool2}
+	toolsMap, toolsets := setUpResources(t, mockTools)
+	ts, shutdown := setUpServer(t, "api", toolsMap, toolsets)
 	defer shutdown()

 	// wantResponse is a struct for checks against test cases
@@ -118,8 +119,9 @@ func TestToolsetEndpoint(t *testing.T) {
 }

 func TestToolGetEndpoint(t *testing.T) {
-	toolsMap, toolsets := setUpResources(t)
-	ts, shutdown := setUpServer(t, toolsMap, toolsets)
+	mockTools := []MockTool{tool1, tool2}
+	toolsMap, toolsets := setUpResources(t, mockTools)
+	ts, shutdown := setUpServer(t, "api", toolsMap, toolsets)
 	defer shutdown()

 	// wantResponse is a struct for checks against test cases
--- a/internal/server/common_test.go
+++ b/internal/server/common_test.go
@@ -21,8 +21,10 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"sync"
 	"testing"

+	"github.com/go-chi/chi/v5"
 	"github.com/googleapis/genai-toolbox/internal/log"
 	"github.com/googleapis/genai-toolbox/internal/telemetry"
 	"github.com/googleapis/genai-toolbox/internal/tools"
@@ -38,6 +40,7 @@ type MockTool struct {
 	Name        string
 	Description string
 	Params      []tools.Parameter
+	manifest    tools.Manifest
 }

 func (t MockTool) Invoke(tools.ParamValues) ([]any, error) {
@@ -61,6 +64,29 @@ func (t MockTool) Authorized(verifiedAuthServices []string) bool {
 	return true
 }

+func (t MockTool) McpManifest() tools.McpManifest {
+	properties := make(map[string]tools.ParameterMcpManifest)
+	required := make([]string, 0)
+
+	for _, p := range t.Params {
+		name := p.GetName()
+		properties[name] = p.McpManifest()
+		required = append(required, name)
+	}
+
+	toolsSchema := tools.McpToolsSchema{
+		Type:       "object",
+		Properties: properties,
+		Required:   required,
+	}
+
+	return tools.McpManifest{
+		Name:        t.Name,
+		Description: t.Description,
+		InputSchema: toolsSchema,
+	}
+}
+
 var tool1 = MockTool{
 	Name:   "no_params",
 	Params: []tools.Parameter{},
@@ -74,15 +100,29 @@ var tool2 = MockTool{
 	},
 }

+var tool3 = MockTool{
+	Name:        "array_param",
+	Description: "some description",
+	Params: tools.Parameters{
+		tools.NewArrayParameter("my_array", "this param is an array of strings", tools.NewStringParameter("my_string", "string item")),
+	},
+}
+
 // setUpResources setups resources to test against
-func setUpResources(t *testing.T) (map[string]tools.Tool, map[string]tools.Toolset) {
-	toolsMap := map[string]tools.Tool{tool1.Name: tool1, tool2.Name: tool2}
+func setUpResources(t *testing.T, mockTools []MockTool) (map[string]tools.Tool, map[string]tools.Toolset) {
+	toolsMap := make(map[string]tools.Tool)
+	var allTools []string
+	for _, tool := range mockTools {
+		tool.manifest = tool.Manifest()
+		toolsMap[tool.Name] = tool
+		allTools = append(allTools, tool.Name)
+	}

 	toolsets := make(map[string]tools.Toolset)
 	for name, l := range map[string][]string{
-		"":           {tool1.Name, tool2.Name},
-		"tool1_only": {tool1.Name},
-		"tool2_only": {tool2.Name},
+		"":           allTools,
+		"tool1_only": {allTools[0]},
+		"tool2_only": {allTools[1]},
 	} {
 		tc := tools.ToolsetConfig{Name: name, ToolNames: l}
 		m, err := tc.Initialize(fakeVersionString, toolsMap)
@@ -95,7 +135,7 @@ func setUpResources(t *testing.T) (map[string]tools.Tool, map[string]tools.Tools
 }

 // setUpServer create a new server with tools and toolsets that are given
-func setUpServer(t *testing.T, tools map[string]tools.Tool, toolsets map[string]tools.Toolset) (*httptest.Server, func()) {
+func setUpServer(t *testing.T, router string, tools map[string]tools.Tool, toolsets map[string]tools.Toolset) (*httptest.Server, func()) {
 	ctx, cancel := context.WithCancel(context.Background())

 	testLogger, err := log.NewStdLogger(os.Stdout, os.Stderr, "info")
@@ -113,10 +153,26 @@ func setUpServer(t *testing.T, tools map[string]tools.Tool, toolsets map[string]
 		t.Fatalf("unable to create custom metrics: %s", err)
 	}

-	server := Server{version: fakeVersionString, logger: testLogger, instrumentation: instrumentation, tools: tools, toolsets: toolsets}
-	r, err := apiRouter(&server)
-	if err != nil {
-		t.Fatalf("unable to initialize router: %s", err)
+	sseManager := &sseManager{
+		mu:          sync.RWMutex{},
+		sseSessions: make(map[string]*sseSession),
+	}
+
+	server := Server{version: fakeVersionString, logger: testLogger, instrumentation: instrumentation, sseManager: sseManager, tools: tools, toolsets: toolsets}
+	var r chi.Router
+	switch router {
+	case "api":
+		r, err = apiRouter(&server)
+		if err != nil {
+			t.Fatalf("unable to initialize api router: %s", err)
+		}
+	case "mcp":
+		r, err = mcpRouter(&server)
+		if err != nil {
+			t.Fatalf("unable to initialize mcp router: %s", err)
+		}
+	default:
+		t.Fatalf("unknown router")
 	}
 	ts := httptest.NewServer(r)
 	shutdown := func() {
--- a/internal/server/instrumentation.go
+++ b/internal/server/instrumentation.go
@@ -29,6 +29,8 @@ const (
 	toolsetGetCountName = "toolbox.server.toolset.get.count"
 	toolGetCountName    = "toolbox.server.tool.get.count"
 	toolInvokeCountName = "toolbox.server.tool.invoke.count"
+	mcpSseCountName     = "toolbox.server.mcp.sse.count"
+	mcpPostCountName    = "toolbox.server.mcp.post.count"
 )

 // Instrumentation defines the telemetry instrumentation for toolbox
@@ -38,6 +40,8 @@ type Instrumentation struct {
 	ToolsetGet metric.Int64Counter
 	ToolGet    metric.Int64Counter
 	ToolInvoke metric.Int64Counter
+	McpSse     metric.Int64Counter
+	McpPost    metric.Int64Counter
 }

 func CreateTelemetryInstrumentation(versionString string) (*Instrumentation, error) {
@@ -74,12 +78,32 @@ func CreateTelemetryInstrumentation(versionString string) (*Instrumentation, err
 		return nil, fmt.Errorf("unable to create %s metric: %w", toolInvokeCountName, err)
 	}

+	mcpSse, err := meter.Int64Counter(
+		mcpSseCountName,
+		metric.WithDescription("Number of MCP SSE connection requests."),
+		metric.WithUnit("{connection}"),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create %s metric: %w", mcpSseCountName, err)
+	}
+
+	mcpPost, err := meter.Int64Counter(
+		mcpPostCountName,
+		metric.WithDescription("Number of MCP Post calls."),
+		metric.WithUnit("{call}"),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create %s metric: %w", mcpPostCountName, err)
+	}
+
 	instrumentation := &Instrumentation{
 		Tracer:     tracer,
 		meter:      meter,
 		ToolsetGet: toolsetGet,
 		ToolGet:    toolGet,
 		ToolInvoke: toolInvoke,
+		McpSse:     mcpSse,
+		McpPost:    mcpPost,
 	}
 	return instrumentation, nil
 }
--- a/internal/server/mcp.go
+++ b/internal/server/mcp.go
@@ -0,0 +1,363 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package server
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/go-chi/render"
+	"github.com/google/uuid"
+	"github.com/googleapis/genai-toolbox/internal/server/mcp"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/metric"
+)
+
+type sseSession struct {
+	sessionId  string
+	writer     http.ResponseWriter
+	flusher    http.Flusher
+	done       chan struct{}
+	eventQueue chan string
+}
+
+// sseManager manages and control access to sse sessions
+type sseManager struct {
+	mu          sync.RWMutex
+	sseSessions map[string]*sseSession
+}
+
+func (m *sseManager) get(id string) (*sseSession, bool) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	session, ok := m.sseSessions[id]
+	return session, ok
+}
+
+func (m *sseManager) add(id string, session *sseSession) {
+	m.mu.Lock()
+	m.sseSessions[id] = session
+	m.mu.Unlock()
+}
+
+func (m *sseManager) remove(id string) {
+	m.mu.Lock()
+	delete(m.sseSessions, id)
+	m.mu.Unlock()
+}
+
+// mcpRouter creates a router that represents the routes under /mcp
+func mcpRouter(s *Server) (chi.Router, error) {
+	r := chi.NewRouter()
+
+	r.Use(middleware.AllowContentType("application/json"))
+	r.Use(middleware.StripSlashes)
+	r.Use(render.SetContentType(render.ContentTypeJSON))
+
+	r.Get("/sse", func(w http.ResponseWriter, r *http.Request) { sseHandler(s, w, r) })
+	r.Post("/", func(w http.ResponseWriter, r *http.Request) { mcpHandler(s, w, r) })
+
+	return r, nil
+}
+
+// sseHandler handles sse initialization and message.
+func sseHandler(s *Server, w http.ResponseWriter, r *http.Request) {
+	ctx, span := s.instrumentation.Tracer.Start(r.Context(), "toolbox/server/mcp/sse")
+	r = r.WithContext(ctx)
+
+	sessionId := uuid.New().String()
+	span.SetAttributes(attribute.String("session_id", sessionId))
+
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+
+	var err error
+	defer func() {
+		if err != nil {
+			span.SetStatus(codes.Error, err.Error())
+		}
+		span.End()
+		status := "success"
+		if err != nil {
+			status = "error"
+		}
+		s.instrumentation.McpSse.Add(
+			r.Context(),
+			1,
+			metric.WithAttributes(attribute.String("toolbox.sse.sessionId", sessionId)),
+			metric.WithAttributes(attribute.String("toolbox.operation.status", status)),
+		)
+	}()
+
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		err = fmt.Errorf("unable to retrieve flusher for sse")
+		s.logger.DebugContext(ctx, err.Error())
+		_ = render.Render(w, r, newErrResponse(err, http.StatusInternalServerError))
+	}
+	session := &sseSession{
+		sessionId:  sessionId,
+		writer:     w,
+		flusher:    flusher,
+		done:       make(chan struct{}),
+		eventQueue: make(chan string, 100),
+	}
+	s.sseManager.add(sessionId, session)
+	defer s.sseManager.remove(sessionId)
+
+	// send initial endpoint event
+	messageEndpoint := fmt.Sprintf("http://%s/mcp?sessionId=%s", r.Host, sessionId)
+	s.logger.DebugContext(ctx, fmt.Sprintf("sending endpoint event: %s", messageEndpoint))
+	fmt.Fprintf(w, "event: endpoint\ndata: %s\n\n", messageEndpoint)
+	flusher.Flush()
+
+	clientClose := r.Context().Done()
+	for {
+		select {
+		// Ensure that only a single responses are written at once
+		case event := <-session.eventQueue:
+			fmt.Fprint(w, event)
+			s.logger.DebugContext(ctx, fmt.Sprintf("sending event: %s", event))
+			flusher.Flush()
+			// channel for client disconnection
+		case <-clientClose:
+			close(session.done)
+			s.logger.DebugContext(ctx, "client disconnected")
+			return
+		}
+	}
+}
+
+// mcpHandler handles all mcp messages.
+func mcpHandler(s *Server, w http.ResponseWriter, r *http.Request) {
+	ctx, span := s.instrumentation.Tracer.Start(r.Context(), "toolbox/server/mcp")
+	r = r.WithContext(ctx)
+
+	var id, toolName, method string
+	var err error
+	defer func() {
+		if err != nil {
+			span.SetStatus(codes.Error, err.Error())
+		}
+		span.End()
+
+		status := "success"
+		if err != nil {
+			status = "error"
+		}
+		s.instrumentation.McpPost.Add(
+			r.Context(),
+			1,
+			metric.WithAttributes(attribute.String("toolbox.sse.sessionId", id)),
+			metric.WithAttributes(attribute.String("toolbox.name", toolName)),
+			metric.WithAttributes(attribute.String("toolbox.method", method)),
+			metric.WithAttributes(attribute.String("toolbox.operation.status", status)),
+		)
+	}()
+
+	// Read and returns a body from io.Reader
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		// Generate a new uuid if unable to decode
+		id = uuid.New().String()
+		s.logger.DebugContext(ctx, err.Error())
+		render.JSON(w, r, newJSONRPCError(id, mcp.PARSE_ERROR, err.Error(), nil))
+	}
+
+	// Generic baseMessage could either be a JSONRPCNotification or JSONRPCRequest
+	var baseMessage struct {
+		Jsonrpc string        `json:"jsonrpc"`
+		Method  string        `json:"method"`
+		Id      mcp.RequestId `json:"id,omitempty"`
+	}
+	if err = decodeJSON(bytes.NewBuffer(body), &baseMessage); err != nil {
+		// Generate a new uuid if unable to decode
+		id := uuid.New().String()
+		s.logger.DebugContext(ctx, err.Error())
+		render.JSON(w, r, newJSONRPCError(id, mcp.PARSE_ERROR, err.Error(), nil))
+		return
+	}
+
+	// Check if method is present
+	if baseMessage.Method == "" {
+		err = fmt.Errorf("method not found")
+		s.logger.DebugContext(ctx, err.Error())
+		render.JSON(w, r, newJSONRPCError(baseMessage.Id, mcp.METHOD_NOT_FOUND, err.Error(), nil))
+		return
+	}
+
+	// Check for JSON-RPC 2.0
+	if baseMessage.Jsonrpc != mcp.JSONRPC_VERSION {
+		err = fmt.Errorf("invalid json-rpc version")
+		s.logger.DebugContext(ctx, err.Error())
+		render.JSON(w, r, newJSONRPCError(baseMessage.Id, mcp.INVALID_REQUEST, err.Error(), nil))
+		return
+	}
+
+	// Check if message is a notification
+	if baseMessage.Id == nil {
+		id = ""
+		var notification mcp.JSONRPCNotification
+		if err = json.Unmarshal(body, &notification); err != nil {
+			err = fmt.Errorf("invalid notification request: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			render.JSON(w, r, newJSONRPCError(baseMessage.Id, mcp.PARSE_ERROR, err.Error(), nil))
+		}
+		// Notifications do not expect a response
+		// Toolbox doesn't do anything with notifications yet
+		w.WriteHeader(http.StatusAccepted)
+		return
+	}
+	id = fmt.Sprintf("%s", baseMessage.Id)
+	method = baseMessage.Method
+
+	var res mcp.JSONRPCMessage
+	switch baseMessage.Method {
+	case "initialize":
+		var req mcp.InitializeRequest
+		if err = json.Unmarshal(body, &req); err != nil {
+			err = fmt.Errorf("invalid mcp initialize request: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_REQUEST, err.Error(), nil)
+			break
+		}
+		result := mcp.Initialize(s.version)
+		res = mcp.JSONRPCResponse{
+			Jsonrpc: mcp.JSONRPC_VERSION,
+			Id:      baseMessage.Id,
+			Result:  result,
+		}
+	case "tools/list":
+		var req mcp.ListToolsRequest
+		if err = json.Unmarshal(body, &req); err != nil {
+			err = fmt.Errorf("invalid mcp tools list request: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_REQUEST, err.Error(), nil)
+			break
+		}
+		toolset, ok := s.toolsets[""]
+		if !ok {
+			err = fmt.Errorf("toolset does not exist")
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_REQUEST, err.Error(), nil)
+			break
+		}
+		result := mcp.ToolsList(toolset)
+		res = mcp.JSONRPCResponse{
+			Jsonrpc: mcp.JSONRPC_VERSION,
+			Id:      baseMessage.Id,
+			Result:  result,
+		}
+	case "tools/call":
+		var req mcp.CallToolRequest
+		if err = json.Unmarshal(body, &req); err != nil {
+			err = fmt.Errorf("invalid mcp tools call request: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_REQUEST, err.Error(), nil)
+			break
+		}
+		toolName = req.Params.Name
+		toolArgument := req.Params.Arguments
+		tool, ok := s.tools[toolName]
+		if !ok {
+			err = fmt.Errorf("invalid tool name: tool with name %q does not exist", toolName)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_PARAMS, err.Error(), nil)
+			break
+		}
+
+		// marshal arguments and decode it using decodeJSON instead to prevent loss between floats/int.
+		aMarshal, err := json.Marshal(toolArgument)
+		if err != nil {
+			err = fmt.Errorf("unable to marshal tools argument: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INTERNAL_ERROR, err.Error(), nil)
+			break
+		}
+		var data map[string]any
+		if err = decodeJSON(bytes.NewBuffer(aMarshal), &data); err != nil {
+			err = fmt.Errorf("unable to decode tools argument: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INTERNAL_ERROR, err.Error(), nil)
+			break
+		}
+
+		// claimsFromAuth maps the name of the authservice to the claims retrieved from it.
+		// Since MCP doesn't support auth, an empty map will be use every time.
+		claimsFromAuth := make(map[string]map[string]any)
+
+		params, err := tool.ParseParams(data, claimsFromAuth)
+		if err != nil {
+			err = fmt.Errorf("provided parameters were invalid: %w", err)
+			s.logger.DebugContext(ctx, err.Error())
+			res = newJSONRPCError(baseMessage.Id, mcp.INVALID_PARAMS, err.Error(), nil)
+			break
+		}
+
+		result := mcp.ToolCall(tool, params)
+		res = mcp.JSONRPCResponse{
+			Jsonrpc: mcp.JSONRPC_VERSION,
+			Id:      baseMessage.Id,
+			Result:  result,
+		}
+	default:
+		err = fmt.Errorf("invalid method %s", baseMessage.Method)
+		s.logger.DebugContext(ctx, err.Error())
+		res = newJSONRPCError(baseMessage.Id, mcp.METHOD_NOT_FOUND, err.Error(), nil)
+	}
+
+	// retrieve sse session
+	sessionId := r.URL.Query().Get("sessionId")
+	session, ok := s.sseManager.get(sessionId)
+	if !ok {
+		s.logger.DebugContext(ctx, "sse session not available")
+	} else {
+		// queue sse event
+		eventData, _ := json.Marshal(res)
+		select {
+		case session.eventQueue <- fmt.Sprintf("event: message\ndata: %s\n\n", eventData):
+			s.logger.DebugContext(ctx, "event queue successful")
+		case <-session.done:
+			s.logger.DebugContext(ctx, "session is close")
+		default:
+			s.logger.DebugContext(ctx, "unable to add to event queue")
+		}
+	}
+
+	// send HTTP response
+	render.JSON(w, r, res)
+}
+
+// newJSONRPCError is the response sent back when an error has been encountered in mcp.
+func newJSONRPCError(id mcp.RequestId, code int, message string, data any) mcp.JSONRPCError {
+	return mcp.JSONRPCError{
+		Jsonrpc: mcp.JSONRPC_VERSION,
+		Id:      id,
+		Error: mcp.McpError{
+			Code:    code,
+			Message: message,
+			Data:    data,
+		},
+	}
+}
--- a/internal/server/mcp/method.go
+++ b/internal/server/mcp/method.go
@@ -0,0 +1,74 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package mcp
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/googleapis/genai-toolbox/internal/tools"
+)
+
+func Initialize(version string) InitializeResult {
+	toolsListChanged := false
+	result := InitializeResult{
+		ProtocolVersion: LATEST_PROTOCOL_VERSION,
+		Capabilities: ServerCapabilities{
+			Tools: &ListChanged{
+				ListChanged: &toolsListChanged,
+			},
+		},
+		ServerInfo: Implementation{
+			Name:    SERVER_NAME,
+			Version: version,
+		},
+	}
+	return result
+}
+
+// ToolsList return a ListToolsResult
+func ToolsList(toolset tools.Toolset) ListToolsResult {
+	mcpManifest := toolset.McpManifest
+
+	result := ListToolsResult{
+		Tools: mcpManifest,
+	}
+	return result
+}
+
+// ToolCall runs tool invocation and return a CallToolResult
+func ToolCall(tool tools.Tool, params tools.ParamValues) CallToolResult {
+	res, err := tool.Invoke(params)
+	if err != nil {
+		text := TextContent{
+			Type: "text",
+			Text: err.Error(),
+		}
+		return CallToolResult{Content: []TextContent{text}, IsError: true}
+	}
+
+	content := make([]TextContent, 0)
+	for _, d := range res {
+		text := TextContent{Type: "text"}
+		dM, err := json.Marshal(d)
+		if err != nil {
+			text.Text = fmt.Sprintf("fail to marshal: %s, result: %s", err, d)
+		} else {
+			text.Text = string(dM)
+		}
+		content = append(content, text)
+	}
+	return CallToolResult{Content: content}
+}
--- a/internal/server/mcp/types.go
+++ b/internal/server/mcp/types.go
@@ -0,0 +1,295 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package mcp
+
+import (
+	"github.com/googleapis/genai-toolbox/internal/tools"
+)
+
+// SERVER_NAME is the server name used in Implementation.
+const SERVER_NAME = "Toolbox"
+
+// LATEST_PROTOCOL_VERSION is the most recent version of the MCP protocol.
+const LATEST_PROTOCOL_VERSION = "2024-11-05"
+
+// JSONRPC_VERSION is the version of JSON-RPC used by MCP.
+const JSONRPC_VERSION = "2.0"
+
+// Standard JSON-RPC error codes
+const (
+	PARSE_ERROR      = -32700
+	INVALID_REQUEST  = -32600
+	METHOD_NOT_FOUND = -32601
+	INVALID_PARAMS   = -32602
+	INTERNAL_ERROR   = -32603
+)
+
+// JSONRPCMessage represents either a JSONRPCRequest, JSONRPCNotification, JSONRPCResponse, or JSONRPCError.
+type JSONRPCMessage interface{}
+
+// ProgressToken is used to associate progress notifications with the original request.
+type ProgressToken interface{}
+
+// Request represents a bidirectional message with method and parameters expecting a response.
+type Request struct {
+	Method string `json:"method"`
+	Params struct {
+		Meta struct {
+			// If specified, the caller is requesting out-of-band progress
+			// notifications for this request (as represented by
+			// notifications/progress). The value of this parameter is an
+			// opaque token that will be attached to any subsequent
+			// notifications. The receiver is not obligated to provide these
+			// notifications.
+			ProgressToken ProgressToken `json:"progressToken,omitempty"`
+		} `json:"_meta,omitempty"`
+	} `json:"params,omitempty"`
+}
+
+// Notification is a one-way message requiring no response.
+type Notification struct {
+	Method string `json:"method"`
+	Params struct {
+		Meta map[string]interface{} `json:"_meta,omitempty"`
+	} `json:"params,omitempty"`
+}
+
+// Result represents a response for the request query.
+type Result struct {
+	// This result property is reserved by the protocol to allow clients and
+	// servers to attach additional metadata to their responses.
+	Meta map[string]interface{} `json:"_meta,omitempty"`
+}
+
+// RequestId is a uniquely identifying ID for a request in JSON-RPC.
+// It can be any JSON-serializable value, typically a number or string.
+type RequestId interface{}
+
+// JSONRPCRequest represents a request that expects a response.
+type JSONRPCRequest struct {
+	Jsonrpc string    `json:"jsonrpc"`
+	Id      RequestId `json:"id"`
+	Request
+	Params any `json:"params,omitempty"`
+}
+
+// JSONRPCNotification represents a notification which does not expect a response.
+type JSONRPCNotification struct {
+	Jsonrpc string `json:"jsonrpc"`
+	Notification
+}
+
+// JSONRPCResponse represents a successful (non-error) response to a request.
+type JSONRPCResponse struct {
+	Jsonrpc string      `json:"jsonrpc"`
+	Id      RequestId   `json:"id"`
+	Result  interface{} `json:"result"`
+}
+
+// McpError represents the error content.
+type McpError struct {
+	// The error type that occurred.
+	Code int `json:"code"`
+	// A short description of the error. The message SHOULD be limited
+	// to a concise single sentence.
+	Message string `json:"message"`
+	// Additional information about the error. The value of this member
+	// is defined by the sender (e.g. detailed error information, nested errors etc.).
+	Data interface{} `json:"data,omitempty"`
+}
+
+// JSONRPCError represents a non-successful (error) response to a request.
+type JSONRPCError struct {
+	Jsonrpc string    `json:"jsonrpc"`
+	Id      RequestId `json:"id"`
+	Error   McpError  `json:"error"`
+}
+
+/* Empty result */
+
+// EmptyResult represents a response that indicates success but carries no data.
+type EmptyResult Result
+
+/* Initialization */
+
+// Params to define MCP Client during initialize request.
+type InitializeParams struct {
+	// The latest version of the Model Context Protocol that the client supports.
+	// The client MAY decide to support older versions as well.
+	ProtocolVersion string             `json:"protocolVersion"`
+	Capabilities    ClientCapabilities `json:"capabilities"`
+	ClientInfo      Implementation     `json:"clientInfo"`
+}
+
+// InitializeRequest is sent from the client to the server when it first
+// connects, asking it to begin initialization.
+type InitializeRequest struct {
+	Request
+	Params InitializeParams `json:"params"`
+}
+
+// InitializeResult is sent after receiving an initialize request from the
+// client.
+type InitializeResult struct {
+	Result
+	// The version of the Model Context Protocol that the server wants to use.
+	// This may not match the version that the client requested. If the client cannot
+	// support this version, it MUST disconnect.
+	ProtocolVersion string             `json:"protocolVersion"`
+	Capabilities    ServerCapabilities `json:"capabilities"`
+	ServerInfo      Implementation     `json:"serverInfo"`
+	// Instructions describing how to use the server and its features.
+	//
+	// This can be used by clients to improve the LLM's understanding of
+	// available tools, resources, etc. It can be thought of like a "hint" to the model.
+	// For example, this information MAY be added to the system prompt.
+	Instructions string `json:"instructions,omitempty"`
+}
+
+// InitializedNotification is sent from the client to the server after
+// initialization has finished.
+type InitializedNotification struct {
+	Notification
+}
+
+// ListChange represents whether the server supports notification for changes to the capabilities.
+type ListChanged struct {
+	ListChanged *bool `json:"listChanged,omitempty"`
+}
+
+// ClientCapabilities represents capabilities a client may support. Known
+// capabilities are defined here, in this schema, but this is not a closed set: any
+// client can define its own, additional capabilities.
+type ClientCapabilities struct {
+	// Experimental, non-standard capabilities that the client supports.
+	Experimental map[string]interface{} `json:"experimental,omitempty"`
+	// Present if the client supports listing roots.
+	Roots *ListChanged `json:"roots,omitempty"`
+	// Present if the client supports sampling from an LLM.
+	Sampling struct{} `json:"sampling,omitempty"`
+}
+
+// ServerCapabilities represents capabilities that a server may support. Known
+// capabilities are defined here, in this schema, but this is not a closed set: any
+// server can define its own, additional capabilities.
+type ServerCapabilities struct {
+	Tools *ListChanged `json:"tools,omitempty"`
+}
+
+// Implementation describes the name and version of an MCP implementation.
+type Implementation struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+}
+
+/* Pagination */
+
+// Cursor is an opaque token used to represent a cursor for pagination.
+type Cursor string
+
+type PaginatedRequest struct {
+	Request
+	Params struct {
+		// An opaque token representing the current pagination position.
+		// If provided, the server should return results starting after this cursor.
+		Cursor Cursor `json:"cursor,omitempty"`
+	} `json:"params,omitempty"`
+}
+
+type PaginatedResult struct {
+	Result
+	// An opaque token representing the pagination position after the last returned result.
+	// If present, there may be more results available.
+	NextCursor Cursor `json:"nextCursor,omitempty"`
+}
+
+/* Tools */
+
+// Sent from the client to request a list of tools the server has.
+type ListToolsRequest struct {
+	PaginatedRequest
+}
+
+// The server's response to a tools/list request from the client.
+type ListToolsResult struct {
+	PaginatedResult
+	Tools []tools.McpManifest `json:"tools"`
+}
+
+// Used by the client to invoke a tool provided by the server.
+type CallToolRequest struct {
+	Request
+	Params struct {
+		Name      string         `json:"name"`
+		Arguments map[string]any `json:"arguments,omitempty"`
+	} `json:"params,omitempty"`
+}
+
+// The sender or recipient of messages and data in a conversation.
+type Role string
+
+const (
+	RoleUser      Role = "user"
+	RoleAssistant Role = "assistant"
+)
+
+// Base for objects that include optional annotations for the client.
+// The client can use annotations to inform how objects are used or displayed
+type Annotated struct {
+	Annotations *struct {
+		// Describes who the intended customer of this object or data is.
+		// It can include multiple entries to indicate content useful for multiple
+		// audiences (e.g., `["user", "assistant"]`).
+		Audience []Role `json:"audience,omitempty"`
+		// Describes how important this data is for operating the server.
+		//
+		// A value of 1 means "most important," and indicates that the data is
+		// effectively required, while 0 means "least important," and indicates that
+		// the data is entirely optional.
+		//
+		// @TJS-type number
+		// @minimum 0
+		// @maximum 1
+		Priority float64 `json:"priority,omitempty"`
+	} `json:"annotations,omitempty"`
+}
+
+// TextContent represents text provided to or from an LLM.
+type TextContent struct {
+	Annotated
+	Type string `json:"type"`
+	// The text content of the message.
+	Text string `json:"text"`
+}
+
+// The server's response to a tool call.
+//
+// Any errors that originate from the tool SHOULD be reported inside the result
+// object, with `isError` set to true, _not_ as an MCP protocol-level error
+// response. Otherwise, the LLM would not be able to see that an error occurred
+// and self-correct.
+//
+// However, any errors in _finding_ the tool, an error indicating that the
+// server does not support tool calls, or any other exceptional conditions,
+// should be reported as an MCP error response.
+type CallToolResult struct {
+	Result
+	// Could be either a TextContent, ImageContent, or EmbeddedResources
+	// For Toolbox, we will only be sending TextContent
+	Content []TextContent `json:"content"`
+	// Whether the tool call ended in an error.
+	// If not set, this is assumed to be false (the call was successful).
+	IsError bool `json:"isError,omitempty"`
+}
--- a/internal/server/mcp_test.go
+++ b/internal/server/mcp_test.go
@@ -0,0 +1,258 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package server
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/googleapis/genai-toolbox/internal/server/mcp"
+)
+
+const jsonrpcVersion = "2.0"
+const protocolVersion = "2024-11-05"
+const serverName = "Toolbox"
+
+var tool1InputSchema = map[string]any{
+	"type":       "object",
+	"properties": map[string]any{},
+	"required":   []any{},
+}
+
+var tool2InputSchema = map[string]any{
+	"type": "object",
+	"properties": map[string]any{
+		"param1": map[string]any{"type": "integer", "description": "This is the first parameter."},
+		"param2": map[string]any{"type": "integer", "description": "This is the second parameter."},
+	},
+	"required": []any{"param1", "param2"},
+}
+
+var tool3InputSchema = map[string]any{
+	"type": "object",
+	"properties": map[string]any{
+		"my_array": map[string]any{
+			"type":        "array",
+			"description": "this param is an array of strings",
+			"items":       map[string]any{"type": "string", "description": "string item"},
+		},
+	},
+	"required": []any{"my_array"},
+}
+
+func TestMcpEndpoint(t *testing.T) {
+	mockTools := []MockTool{tool1, tool2, tool3}
+	toolsMap, toolsets := setUpResources(t, mockTools)
+	ts, shutdown := setUpServer(t, "mcp", toolsMap, toolsets)
+	defer shutdown()
+
+	testCases := []struct {
+		name  string
+		isErr bool
+		body  mcp.JSONRPCRequest
+		want  map[string]any
+	}{
+		{
+			name: "initialize",
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: jsonrpcVersion,
+				Id:      "mcp-initialize",
+				Request: mcp.Request{
+					Method: "initialize",
+				},
+			},
+			want: map[string]any{
+				"jsonrpc": "2.0",
+				"id":      "mcp-initialize",
+				"result": map[string]any{
+					"protocolVersion": protocolVersion,
+					"capabilities": map[string]any{
+						"tools": map[string]any{"listChanged": false},
+					},
+					"serverInfo": map[string]any{"name": serverName, "version": fakeVersionString},
+				},
+			},
+		},
+		{
+			name: "basic notification",
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: jsonrpcVersion,
+				Request: mcp.Request{
+					Method: "notification",
+				},
+			},
+		},
+		{
+			name: "tools/list",
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: jsonrpcVersion,
+				Id:      "tools-list",
+				Request: mcp.Request{
+					Method: "tools/list",
+				},
+			},
+			want: map[string]any{
+				"jsonrpc": "2.0",
+				"id":      "tools-list",
+				"result": map[string]any{
+					"tools": []any{
+						map[string]any{
+							"name":        "no_params",
+							"inputSchema": tool1InputSchema,
+						},
+						map[string]any{
+							"name":        "some_params",
+							"inputSchema": tool2InputSchema,
+						},
+						map[string]any{
+							"name":        "array_param",
+							"description": "some description",
+							"inputSchema": tool3InputSchema,
+						},
+					},
+				},
+			},
+		},
+		{
+			name:  "missing method",
+			isErr: true,
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: jsonrpcVersion,
+				Id:      "missing-method",
+				Request: mcp.Request{},
+			},
+			want: map[string]any{
+				"jsonrpc": "2.0",
+				"id":      "missing-method",
+				"error": map[string]any{
+					"code":    -32601.0,
+					"message": "method not found",
+				},
+			},
+		},
+		{
+			name:  "invalid method",
+			isErr: true,
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: jsonrpcVersion,
+				Id:      "invalid-method",
+				Request: mcp.Request{
+					Method: "foo",
+				},
+			},
+			want: map[string]any{
+				"jsonrpc": "2.0",
+				"id":      "invalid-method",
+				"error": map[string]any{
+					"code":    -32601.0,
+					"message": "invalid method foo",
+				},
+			},
+		},
+		{
+			name:  "invalid jsonrpc version",
+			isErr: true,
+			body: mcp.JSONRPCRequest{
+				Jsonrpc: "1.0",
+				Id:      "invalid-jsonrpc-version",
+				Request: mcp.Request{
+					Method: "foo",
+				},
+			},
+			want: map[string]any{
+				"jsonrpc": "2.0",
+				"id":      "invalid-jsonrpc-version",
+				"error": map[string]any{
+					"code":    -32600.0,
+					"message": "invalid json-rpc version",
+				},
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			reqMarshal, err := json.Marshal(tc.body)
+			if err != nil {
+				t.Fatalf("unexpected error during marshaling of body")
+			}
+
+			resp, body, err := runRequest(ts, http.MethodPost, "/", bytes.NewBuffer(reqMarshal))
+			if err != nil {
+				t.Fatalf("unexpected error during request: %s", err)
+			}
+
+			// Notifications don't expect a response.
+			if tc.want != nil {
+				if contentType := resp.Header.Get("Content-type"); contentType != "application/json" {
+					t.Fatalf("unexpected content-type header: want %s, got %s", "application/json", contentType)
+				}
+
+				var got map[string]any
+				if err := json.Unmarshal(body, &got); err != nil {
+					t.Fatalf("unexpected error unmarshalling body: %s", err)
+				}
+				if !reflect.DeepEqual(got, tc.want) {
+					t.Fatalf("unexpected response: got %+v, want %+v", got, tc.want)
+				}
+			}
+		})
+	}
+}
+
+func TestSseEndpoint(t *testing.T) {
+	ts, shutdown := setUpServer(t, "mcp", nil, nil)
+	defer shutdown()
+
+	contentType := "text/event-stream"
+	cacheControl := "no-cache"
+	connection := "keep-alive"
+	accessControlAllowOrigin := "*"
+	wantEvent := "event: endpoint"
+
+	t.Run("test sse endpoint", func(t *testing.T) {
+		resp, err := http.Get(ts.URL + "/sse")
+		if err != nil {
+			t.Fatalf("unexpected error during request: %s", err)
+		}
+		defer resp.Body.Close()
+
+		if gotContentType := resp.Header.Get("Content-type"); gotContentType != contentType {
+			t.Fatalf("unexpected content-type header: want %s, got %s", contentType, gotContentType)
+		}
+		if gotCacheControl := resp.Header.Get("Cache-Control"); gotCacheControl != cacheControl {
+			t.Fatalf("unexpected cache-control header: want %s, got %s", cacheControl, gotCacheControl)
+		}
+		if gotConnection := resp.Header.Get("Connection"); gotConnection != connection {
+			t.Fatalf("unexpected content-type header: want %s, got %s", connection, gotConnection)
+		}
+		if gotAccessControlAllowOrigin := resp.Header.Get("Access-Control-Allow-Origin"); gotAccessControlAllowOrigin != accessControlAllowOrigin {
+			t.Fatalf("unexpected cache-control header: want %s, got %s", accessControlAllowOrigin, gotAccessControlAllowOrigin)
+		}
+
+		buffer := make([]byte, 1024)
+		n, err := resp.Body.Read(buffer)
+		if err != nil {
+			t.Fatalf("unable to read response: %s", err)
+		}
+		endpointEvent := string(buffer[:n])
+		if !strings.Contains(endpointEvent, wantEvent) {
+			t.Fatalf("unexpected event: got %s", endpointEvent)
+		}
+	})
+}
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -20,6 +20,7 @@ import (
 	"net"
 	"net/http"
 	"strconv"
+	"sync"
 	"time"

 	"github.com/go-chi/chi/v5"
@@ -42,6 +43,7 @@ type Server struct {
 	root            chi.Router
 	logger          log.Logger
 	instrumentation *Instrumentation
+	sseManager      *sseManager

 	sources      map[string]sources.Source
 	authServices map[string]auth.AuthService
@@ -203,12 +205,18 @@ func NewServer(ctx context.Context, cfg ServerConfig, l log.Logger) (*Server, er
 	addr := net.JoinHostPort(cfg.Address, strconv.Itoa(cfg.Port))
 	srv := &http.Server{Addr: addr, Handler: r}

+	sseManager := &sseManager{
+		mu:          sync.RWMutex{},
+		sseSessions: make(map[string]*sseSession),
+	}
+
 	s := &Server{
 		version:         cfg.Version,
 		srv:             srv,
 		root:            r,
 		logger:          l,
 		instrumentation: instrumentation,
+		sseManager:      sseManager,

 		sources:      sourcesMap,
 		authServices: authServicesMap,
@@ -221,6 +229,11 @@ func NewServer(ctx context.Context, cfg ServerConfig, l log.Logger) (*Server, er
 		return nil, err
 	}
 	r.Mount("/api", apiR)
+	mcpR, err := mcpRouter(s)
+	if err != nil {
+		return nil, err
+	}
+	r.Mount("/mcp", mcpR)
 	// default endpoint for validating server is running
 	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
 		_, _ = w.Write([]byte("🧰 Hello, World! 🧰"))
--- a/internal/tools/dgraph/dgraph.go
+++ b/internal/tools/dgraph/dgraph.go
@@ -65,6 +65,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
 		Name:         cfg.Name,
@@ -75,6 +81,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		IsQuery:      cfg.IsQuery,
 		Timeout:      cfg.Timeout,
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest:  mcpManifest,
 	}
 	return t, nil
 }
@@ -92,6 +99,7 @@ type Tool struct {
 	Timeout      string
 	Statement    string
 	manifest     tools.Manifest
+	mcpManifest  tools.McpManifest
 }

 func (t Tool) Invoke(params tools.ParamValues) ([]any, error) {
@@ -127,6 +135,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/http/http.go
+++ b/internal/tools/http/http.go
@@ -91,7 +91,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 	// Create a slice for all parameters
 	allParameters := slices.Concat(cfg.BodyParams, cfg.HeaderParams, cfg.QueryParams)

-	// Create parameter manifest
+	// Create parameter MCP manifest
 	paramManifest := slices.Concat(
 		cfg.QueryParams.Manifest(),
 		cfg.BodyParams.Manifest(),
@@ -101,6 +101,36 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		paramManifest = make([]tools.ParameterManifest, 0)
 	}

+	queryMcpManifest := cfg.QueryParams.McpManifest()
+	bodyMcpManifest := cfg.BodyParams.McpManifest()
+	headerMcpManifest := cfg.HeaderParams.McpManifest()
+
+	// Concatenate parameters for MCP `required` field
+	concatRequiredManifest := slices.Concat(
+		queryMcpManifest.Required,
+		bodyMcpManifest.Required,
+		headerMcpManifest.Required,
+	)
+
+	// Concatenate parameters for MCP `properties` field
+	concatPropertiesManifest := make(map[string]tools.ParameterMcpManifest)
+	for name, p := range queryMcpManifest.Properties {
+		concatPropertiesManifest[name] = p
+	}
+	for name, p := range bodyMcpManifest.Properties {
+		concatPropertiesManifest[name] = p
+	}
+	for name, p := range headerMcpManifest.Properties {
+		concatPropertiesManifest[name] = p
+	}
+
+	// Create a new McpToolsSchema with all parameters
+	paramMcpManifest := tools.McpToolsSchema{
+		Type:       "object",
+		Properties: concatPropertiesManifest,
+		Required:   concatRequiredManifest,
+	}
+
 	// Verify there are no duplicate parameter names
 	seenNames := make(map[string]bool)
 	for _, param := range paramManifest {
@@ -110,6 +140,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		seenNames[param.Name] = true
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: paramMcpManifest,
+	}
+
 	// finish tool setup
 	return Tool{
 		Name:         cfg.Name,
@@ -125,6 +161,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		Client:       s.Client,
 		AllParams:    allParameters,
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: paramManifest},
+		mcpManifest:  mcpManifest,
 	}, nil
 }

@@ -146,8 +183,9 @@ type Tool struct {
 	HeaderParams tools.Parameters  `yaml:"headerParams"`
 	AllParams    tools.Parameters  `yaml:"allParams"`

-	Client   *http.Client
-	manifest tools.Manifest
+	Client      *http.Client
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 // helper function to convert a parameter to JSON formatted string.
@@ -271,6 +309,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/mssqlsql/mssqlsql.go
+++ b/internal/tools/mssqlsql/mssqlsql.go
@@ -68,6 +68,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
 		Name:         cfg.Name,
@@ -77,6 +83,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		AuthRequired: cfg.AuthRequired,
 		Db:           s.MSSQLDB(),
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest:  mcpManifest,
 	}
 	return t, nil
 }
@@ -90,9 +97,10 @@ type Tool struct {
 	AuthRequired []string         `yaml:"authRequired"`
 	Parameters   tools.Parameters `yaml:"parameters"`

-	Db        *sql.DB
-	Statement string
-	manifest  tools.Manifest
+	Db          *sql.DB
+	Statement   string
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 func (t Tool) Invoke(params tools.ParamValues) ([]any, error) {
@@ -157,6 +165,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/mysqlsql/mysqlsql.go
+++ b/internal/tools/mysqlsql/mysqlsql.go
@@ -67,6 +67,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
 		Name:         cfg.Name,
@@ -76,6 +82,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		AuthRequired: cfg.AuthRequired,
 		Pool:         s.MySQLPool(),
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest:  mcpManifest,
 	}
 	return t, nil
 }
@@ -89,9 +96,10 @@ type Tool struct {
 	AuthRequired []string         `yaml:"authRequired"`
 	Parameters   tools.Parameters `yaml:"parameters"`

-	Pool      *sql.DB
-	Statement string
-	manifest  tools.Manifest
+	Pool        *sql.DB
+	Statement   string
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 func (t Tool) Invoke(params tools.ParamValues) ([]any, error) {
@@ -152,6 +160,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/neo4j/neo4j.go
+++ b/internal/tools/neo4j/neo4j.go
@@ -66,15 +66,22 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
-		Name:       cfg.Name,
-		Kind:       ToolKind,
-		Parameters: cfg.Parameters,
-		Statement:  cfg.Statement,
-		Driver:     s.Neo4jDriver(),
-		Database:   s.Neo4jDatabase(),
-		manifest:   tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		Name:        cfg.Name,
+		Kind:        ToolKind,
+		Parameters:  cfg.Parameters,
+		Statement:   cfg.Statement,
+		Driver:      s.Neo4jDriver(),
+		Database:    s.Neo4jDatabase(),
+		manifest:    tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest: mcpManifest,
 	}
 	return t, nil
 }
@@ -88,10 +95,11 @@ type Tool struct {
 	Parameters   tools.Parameters `yaml:"parameters"`
 	AuthRequired []string         `yaml:"authRequired"`

-	Driver    neo4j.DriverWithContext
-	Database  string
-	Statement string
-	manifest  tools.Manifest
+	Driver      neo4j.DriverWithContext
+	Database    string
+	Statement   string
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 func (t Tool) Invoke(params tools.ParamValues) ([]any, error) {
@@ -127,6 +135,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/parameters.go
+++ b/internal/tools/parameters.go
@@ -154,6 +154,14 @@ type Parameter interface {
 	GetAuthServices() []ParamAuthService
 	Parse(any) (any, error)
 	Manifest() ParameterManifest
+	McpManifest() ParameterMcpManifest
+}
+
+// McpToolsSchema is the representation of input schema for McpManifest.
+type McpToolsSchema struct {
+	Type       string                          `json:"type"`
+	Properties map[string]ParameterMcpManifest `json:"properties"`
+	Required   []string                        `json:"required"`
 }

 // Parameters is a type used to allow unmarshal a list of parameters
@@ -265,6 +273,24 @@ func (ps Parameters) Manifest() []ParameterManifest {
 	return rtn
 }

+func (ps Parameters) McpManifest() McpToolsSchema {
+	properties := make(map[string]ParameterMcpManifest)
+	required := make([]string, 0)
+
+	for _, p := range ps {
+		name := p.GetName()
+		properties[name] = p.McpManifest()
+		// all parameters are added to the required field
+		required = append(required, name)
+	}
+
+	return McpToolsSchema{
+		Type:       "object",
+		Properties: properties,
+		Required:   required,
+	}
+}
+
 // ParameterManifest represents parameters when served as part of a ToolManifest.
 type ParameterManifest struct {
 	Name         string             `json:"name"`
@@ -274,6 +300,13 @@ type ParameterManifest struct {
 	Items        *ParameterManifest `json:"items,omitempty"`
 }

+// ParameterMcpManifest represents properties when served as part of a ToolMcpManifest.
+type ParameterMcpManifest struct {
+	Type        string                `json:"type"`
+	Description string                `json:"description"`
+	Items       *ParameterMcpManifest `json:"items,omitempty"`
+}
+
 // CommonParameter are default fields that are emebdding in most Parameter implementations. Embedding this stuct will give the object Name() and Type() functions.
 type CommonParameter struct {
 	Name         string             `yaml:"name" validate:"required"`
@@ -308,6 +341,14 @@ func (p *CommonParameter) Manifest() ParameterManifest {
 	}
 }

+// McpManifest returns the MCP manifest for the Parameter.
+func (p *CommonParameter) McpManifest() ParameterMcpManifest {
+	return ParameterMcpManifest{
+		Type:        p.Type,
+		Description: p.Desc,
+	}
+}
+
 // ParseTypeError is a custom error for incorrectly typed Parameters.
 type ParseTypeError struct {
 	Name  string
@@ -611,3 +652,18 @@ func (p *ArrayParameter) Manifest() ParameterManifest {
 		Items:        &items,
 	}
 }
+
+// McpManifest returns the MCP manifest for the ArrayParameter.
+func (p *ArrayParameter) McpManifest() ParameterMcpManifest {
+	// only list ParamAuthService names (without fields) in manifest
+	authNames := make([]string, len(p.AuthServices))
+	for i, a := range p.AuthServices {
+		authNames[i] = a.Name
+	}
+	items := p.Items.McpManifest()
+	return ParameterMcpManifest{
+		Type:        p.Type,
+		Description: p.Desc,
+		Items:       &items,
+	}
+}
--- a/internal/tools/parameters_test.go
+++ b/internal/tools/parameters_test.go
@@ -847,6 +847,52 @@ func TestParamManifest(t *testing.T) {
 	}
 }

+func TestParamMcpManifest(t *testing.T) {
+	tcs := []struct {
+		name string
+		in   tools.Parameter
+		want tools.ParameterMcpManifest
+	}{
+		{
+			name: "string",
+			in:   tools.NewStringParameter("foo-string", "bar"),
+			want: tools.ParameterMcpManifest{Type: "string", Description: "bar"},
+		},
+		{
+			name: "int",
+			in:   tools.NewIntParameter("foo-int", "bar"),
+			want: tools.ParameterMcpManifest{Type: "integer", Description: "bar"},
+		},
+		{
+			name: "float",
+			in:   tools.NewFloatParameter("foo-float", "bar"),
+			want: tools.ParameterMcpManifest{Type: "float", Description: "bar"},
+		},
+		{
+			name: "boolean",
+			in:   tools.NewBooleanParameter("foo-bool", "bar"),
+			want: tools.ParameterMcpManifest{Type: "boolean", Description: "bar"},
+		},
+		{
+			name: "array",
+			in:   tools.NewArrayParameter("foo-array", "bar", tools.NewStringParameter("foo-string", "bar")),
+			want: tools.ParameterMcpManifest{
+				Type:        "array",
+				Description: "bar",
+				Items:       &tools.ParameterMcpManifest{Type: "string", Description: "bar"},
+			},
+		},
+	}
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.in.McpManifest()
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Fatalf("unexpected manifest: got %+v, want %+v", got, tc.want)
+			}
+		})
+	}
+}
+
 func TestFailParametersUnmarshal(t *testing.T) {
 	ctx, err := testutils.ContextWithNewLogger()
 	if err != nil {
--- a/internal/tools/postgressql/postgressql.go
+++ b/internal/tools/postgressql/postgressql.go
@@ -69,6 +69,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
 		Name:         cfg.Name,
@@ -78,6 +84,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		AuthRequired: cfg.AuthRequired,
 		Pool:         s.PostgresPool(),
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest:  mcpManifest,
 	}
 	return t, nil
 }
@@ -91,9 +98,10 @@ type Tool struct {
 	AuthRequired []string         `yaml:"authRequired"`
 	Parameters   tools.Parameters `yaml:"parameters"`

-	Pool      *pgxpool.Pool
-	Statement string
-	manifest  tools.Manifest
+	Pool        *pgxpool.Pool
+	Statement   string
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 func (t Tool) Invoke(params tools.ParamValues) ([]any, error) {
@@ -129,6 +137,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/spanner/spanner.go
+++ b/internal/tools/spanner/spanner.go
@@ -68,6 +68,12 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be one of %q", ToolKind, compatibleSources)
 	}

+	mcpManifest := tools.McpManifest{
+		Name:        cfg.Name,
+		Description: cfg.Description,
+		InputSchema: cfg.Parameters.McpManifest(),
+	}
+
 	// finish tool setup
 	t := Tool{
 		Name:         cfg.Name,
@@ -78,6 +84,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		Client:       s.SpannerClient(),
 		dialect:      s.DatabaseDialect(),
 		manifest:     tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest()},
+		mcpManifest:  mcpManifest,
 	}
 	return t, nil
 }
@@ -91,10 +98,11 @@ type Tool struct {
 	AuthRequired []string         `yaml:"authRequired"`
 	Parameters   tools.Parameters `yaml:"parameters"`

-	Client    *spanner.Client
-	dialect   string
-	Statement string
-	manifest  tools.Manifest
+	Client      *spanner.Client
+	dialect     string
+	Statement   string
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
 }

 func getMapParams(params tools.ParamValues, dialect string) (map[string]interface{}, error) {
@@ -157,6 +165,10 @@ func (t Tool) Manifest() tools.Manifest {
 	return t.manifest
 }

+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
 func (t Tool) Authorized(verifiedAuthServices []string) bool {
 	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
 }
--- a/internal/tools/tools.go
+++ b/internal/tools/tools.go
@@ -29,6 +29,7 @@ type Tool interface {
 	Invoke(ParamValues) ([]any, error)
 	ParseParams(map[string]any, map[string]map[string]any) (ParamValues, error)
 	Manifest() Manifest
+	McpManifest() McpManifest
 	Authorized([]string) bool
 }

@@ -38,6 +39,16 @@ type Manifest struct {
 	Parameters  []ParameterManifest `json:"parameters"`
 }

+// Definition for a tool the MCP client can call.
+type McpManifest struct {
+	// The name of the tool.
+	Name string `json:"name"`
+	// A human-readable description of the tool.
+	Description string `json:"description,omitempty"`
+	// A JSON Schema object defining the expected parameters for the tool.
+	InputSchema McpToolsSchema `json:"inputSchema,omitempty"`
+}
+
 // Helper function that returns if a tool invocation request is authorized
 func IsAuthorized(authRequiredSources []string, verifiedAuthServices []string) bool {
 	if len(authRequiredSources) == 0 {
--- a/internal/tools/toolsets.go
+++ b/internal/tools/toolsets.go
@@ -24,9 +24,10 @@ type ToolsetConfig struct {
 }

 type Toolset struct {
-	Name     string          `yaml:"name"`
-	Tools    []*Tool         `yaml:",inline"`
-	Manifest ToolsetManifest `yaml:",inline"`
+	Name        string          `yaml:"name"`
+	Tools       []*Tool         `yaml:",inline"`
+	Manifest    ToolsetManifest `yaml:",inline"`
+	McpManifest []McpManifest   `yaml:",inline"`
 }

 type ToolsetManifest struct {
@@ -54,6 +55,7 @@ func (t ToolsetConfig) Initialize(serverVersion string, toolsMap map[string]Tool
 		}
 		toolset.Tools = append(toolset.Tools, &tool)
 		toolset.Manifest.ToolsManifest[toolName] = tool.Manifest()
+		toolset.McpManifest = append(toolset.McpManifest, tool.McpManifest())
 	}

 	return toolset, nil
--- a/tests/alloydb_pg_integration_test.go
+++ b/tests/alloydb_pg_integration_test.go
@@ -163,7 +163,9 @@ func TestAlloyDBToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"?column?\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: ERROR: syntax error at or near \"SELEC\" (SQLSTATE 42601)"}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }

 // Test connection with different IP type
--- a/tests/cloud_sql_mssql_integration_test.go
+++ b/tests/cloud_sql_mssql_integration_test.go
@@ -150,7 +150,9 @@ func TestCloudSQLMssqlToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: mssql: Could not find stored procedure 'SELEC'."}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }

 // Test connection with different IP type
--- a/tests/cloud_sql_mysql_integration_test.go
+++ b/tests/cloud_sql_mysql_integration_test.go
@@ -145,7 +145,9 @@ func TestCloudSQLMySQLToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"1\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: Error 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELEC 1' at line 1"}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }

 // Test connection with different IP type
--- a/tests/cloud_sql_pg_integration_test.go
+++ b/tests/cloud_sql_pg_integration_test.go
@@ -149,7 +149,9 @@ func TestCloudSQLPgSimpleToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"?column?\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: ERROR: syntax error at or near \"SELEC\" (SQLSTATE 42601)"}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }

 // Test connection with different IP type
--- a/tests/common_test.go
+++ b/tests/common_test.go
@@ -93,6 +93,12 @@ func GetToolsConfig(sourceConfig map[string]any, toolKind, param_tool_statement,
 					"my-google-auth",
 				},
 			},
+			"my-fail-tool": map[string]any{
+				"kind":        toolKind,
+				"source":      "my-instance",
+				"description": "Tool to test statement with incorrect syntax.",
+				"statement":   "SELEC 1;",
+			},
 		},
 	}

--- a/tests/mssql_integration_test.go
+++ b/tests/mssql_integration_test.go
@@ -122,5 +122,7 @@ func TestMsSQLToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: mssql: Could not find stored procedure 'SELEC'."}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }
--- a/tests/mysql_integration_test.go
+++ b/tests/mysql_integration_test.go
@@ -121,5 +121,7 @@ func TestMySQLToolEndpoints(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"1\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: Error 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELEC 1' at line 1"}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }
--- a/tests/postgres_integration_test.go
+++ b/tests/postgres_integration_test.go
@@ -121,5 +121,7 @@ func TestPostgres(t *testing.T) {
 	RunToolGetTest(t)

 	select_1_want := "[{\"?column?\":1}]"
+	fail_invocation_want := `{"jsonrpc":"2.0","id":"invoke-fail-tool","result":{"content":[{"type":"text","text":"unable to execute query: ERROR: syntax error at or near \"SELEC\" (SQLSTATE 42601)"}],"isError":true}}`
 	RunToolInvokeTest(t, select_1_want)
+	RunMCPToolCallMethod(t, fail_invocation_want)
 }
--- a/tests/tool_test.go
+++ b/tests/tool_test.go
@@ -28,6 +28,7 @@ import (
 	"strings"
 	"testing"

+	"github.com/googleapis/genai-toolbox/internal/server/mcp"
 	"github.com/jackc/pgx/v5/pgxpool"
 )

@@ -304,3 +305,136 @@ func RunToolInvokeTest(t *testing.T, select_1_want string) {
 		})
 	}
 }
+
+// RunMCPToolCallMethod runs the tool/call for mcp endpoint
+func RunMCPToolCallMethod(t *testing.T, fail_invocation_want string) {
+	// Test tool invoke endpoint
+	invokeTcs := []struct {
+		name          string
+		api           string
+		requestBody   mcp.JSONRPCRequest
+		requestHeader map[string]string
+		want          string
+	}{
+		{
+			name:          "MCP Invoke my-param-tool",
+			api:           "http://127.0.0.1:5000/mcp",
+			requestHeader: map[string]string{},
+			requestBody: mcp.JSONRPCRequest{
+				Jsonrpc: "2.0",
+				Id:      "my-param-tool",
+				Request: mcp.Request{
+					Method: "tools/call",
+				},
+				Params: map[string]any{
+					"name": "my-param-tool",
+					"arguments": map[string]any{
+						"id":   int(3),
+						"name": "Alice",
+					},
+				},
+			},
+			want: `{"jsonrpc":"2.0","id":"my-param-tool","result":{"content":[{"type":"text","text":"{\"id\":1,\"name\":\"Alice\"}"},{"type":"text","text":"{\"id\":3,\"name\":\"Sid\"}"}]}}`,
+		},
+		{
+			name:          "MCP Invoke invalid tool",
+			api:           "http://127.0.0.1:5000/mcp",
+			requestHeader: map[string]string{},
+			requestBody: mcp.JSONRPCRequest{
+				Jsonrpc: "2.0",
+				Id:      "invalid-tool",
+				Request: mcp.Request{
+					Method: "tools/call",
+				},
+				Params: map[string]any{
+					"name":      "foo",
+					"arguments": map[string]any{},
+				},
+			},
+			want: `{"jsonrpc":"2.0","id":"invalid-tool","error":{"code":-32602,"message":"invalid tool name: tool with name \"foo\" does not exist"}}`,
+		},
+		{
+			name:          "MCP Invoke my-tool without parameters",
+			api:           "http://127.0.0.1:5000/mcp",
+			requestHeader: map[string]string{},
+			requestBody: mcp.JSONRPCRequest{
+				Jsonrpc: "2.0",
+				Id:      "invoke-without-parameter",
+				Request: mcp.Request{
+					Method: "tools/call",
+				},
+				Params: map[string]any{
+					"name":      "my-tool",
+					"arguments": map[string]any{},
+				},
+			},
+			want: `{"jsonrpc":"2.0","id":"invoke-without-parameter","error":{"code":-32602,"message":"invalid tool name: tool with name \"my-tool\" does not exist"}}`,
+		},
+		{
+			name:          "MCP Invoke my-tool with insufficient parameters",
+			api:           "http://127.0.0.1:5000/mcp",
+			requestHeader: map[string]string{},
+			requestBody: mcp.JSONRPCRequest{
+				Jsonrpc: "2.0",
+				Id:      "invoke-insufficient-parameter",
+				Request: mcp.Request{
+					Method: "tools/call",
+				},
+				Params: map[string]any{
+					"name":      "my-tool",
+					"arguments": map[string]any{"id": 1},
+				},
+			},
+			want: `{"jsonrpc":"2.0","id":"invoke-insufficient-parameter","error":{"code":-32602,"message":"invalid tool name: tool with name \"my-tool\" does not exist"}}`,
+		},
+		{
+			name:          "MCP Invoke my-fail-tool",
+			api:           "http://127.0.0.1:5000/mcp",
+			requestHeader: map[string]string{},
+			requestBody: mcp.JSONRPCRequest{
+				Jsonrpc: "2.0",
+				Id:      "invoke-fail-tool",
+				Request: mcp.Request{
+					Method: "tools/call",
+				},
+				Params: map[string]any{
+					"name":      "my-fail-tool",
+					"arguments": map[string]any{"id": 1},
+				},
+			},
+			want: fail_invocation_want,
+		},
+	}
+	for _, tc := range invokeTcs {
+		t.Run(tc.name, func(t *testing.T) {
+			reqMarshal, err := json.Marshal(tc.requestBody)
+			if err != nil {
+				t.Fatalf("unexpected error during marshaling of request body")
+			}
+			// Send Tool invocation request
+			req, err := http.NewRequest(http.MethodPost, tc.api, bytes.NewBuffer(reqMarshal))
+			if err != nil {
+				t.Fatalf("unable to create request: %s", err)
+			}
+			req.Header.Add("Content-type", "application/json")
+			for k, v := range tc.requestHeader {
+				req.Header.Add(k, v)
+			}
+			resp, err := http.DefaultClient.Do(req)
+			if err != nil {
+				t.Fatalf("unable to send request: %s", err)
+			}
+			respBody, err := io.ReadAll(resp.Body)
+			if err != nil {
+				t.Fatalf("unable to read request body: %s", err)
+			}
+			defer resp.Body.Close()
+			got := string(bytes.TrimSpace(respBody))
+
+			if got != tc.want {
+				fmt.Printf("res is %s\n\n", got)
+				t.Fatalf("unexpected value: got %q, want %q", got, tc.want)
+			}
+		})
+	}
+}