MCP Go SDK

https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk
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An official Go software development kit for the Model Context Protocol that enables building MCP...
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### Run Proxy Example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/proxy

Command to execute the proxy header propagation example.

```bash
go run main.go
```

--------------------------------

### Run the server in standard I/O mode

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Starts the sequential thinking MCP server using standard input/output transport. Run from the example directory.

```bash
go run .
```

--------------------------------

### Start

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/internal/oauthtest

Starts the HTTP server for the FakeIdPServer and registers a cleanup function on the testing.TB.

```APIDOC
## Start

### Description
Starts the HTTP server and registers a cleanup function on the provided testing.TB.

### Method
func (s *FakeIdPServer) Start(t testing.TB)

### Parameters
- **t** (testing.TB) - Required - The testing context used for cleanup registration.
```

--------------------------------

### Start a thinking session with start_thinking

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Example JSON-RPC request to call the start_thinking tool. It begins a new sequential thinking session with a problem statement, optional session ID, and estimated steps.

```json
{
  "method": "tools/call",
  "params": {
    "name": "start_thinking",
    "arguments": {
      "problem": "How should I design a scalable microservices architecture?",
      "sessionId": "architecture_design",
      "estimatedSteps": 8
    }
  }
}
```

--------------------------------

### Review the complete process with review_thinking

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Example JSON-RPC request to call the review_thinking tool to get a complete review of the thinking process for a session.

```json
{
  "method": "tools/call",
  "params": {
    "name": "review_thinking", 
    "arguments": {
      "sessionId": "architecture_design"
    }
  }
}
```

--------------------------------

### AddReceivingCustomMethod usage example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Example of defining custom params and result types and registering a custom method handler with AddReceivingCustomMethod. The handler returns a SearchResult with a single hit.

```go
type SearchParams struct {
    mcp.ParamsBase
    Query string `json:"query"`
}

type SearchResult struct {
    mcp.ResultBase
    Hits []string `json:"hits"`
}

if err := mcp.AddReceivingCustomMethod(server, "acme/search",
    func(ctx context.Context, ss *mcp.ServerSession, params *SearchParams) (*SearchResult, error) {
        return &SearchResult{Hits: []string{"result"}}, nil
    }); err != nil {
    return err
}
```

--------------------------------

### StreamableHTTPHandler Middleware Example Output

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Example output from a middleware test showing a POST request with an initialize method.

```json
POST {"jsonrpc": "2.0", "id": 1, "method":"initialize", "params": {}}

```

--------------------------------

### Roots output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for roots.

```text
Output:
[file://a file://b]
```

--------------------------------

### Prompts output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for prompts.

```text
Output:
greet
user Say hi to Pat
```

--------------------------------

### Progress output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for progress reporting.

```text
Output:
frobbing widgets 0/2
frobbing widgets 1/2
frobbing widgets 2/2
```

--------------------------------

### AddSendingCustomMethod usage example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Example of registering a custom method on a client and later invoking it with CallCustomMethod. The registration uses AddSendingCustomMethod with type parameters, and the invocation uses CallCustomMethod with a SearchParams query.

```go
if err := mcp.AddSendingCustomMethod[*SearchParams, *SearchResult](c, "acme/search"); err != nil {
    return err
}
// ... later, anywhere a *ClientSession is available:
result, err := mcp.CallCustomMethod[*SearchParams, *SearchResult](
    ctx, cs, "acme/search", &SearchParams{Query: "hello"})
```

--------------------------------

### Proxy Example Output

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/proxy

Expected console output showing the backend and gateway startup, header reception, and client result.

```text
2025/08/29 10:00:00 Starting Backend Server on :8082
2025/08/29 10:00:00 Starting Gateway Server on :8081
2025/08/29 10:00:00 Gateway received headers: map[...]
2025/08/29 10:00:00 Client received result: ...
```

--------------------------------

### Resources output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for resource operations.

```text
Output:
file:///a
file:///dir/{f}
a
x
calling "resources/read": Resource not found
```

--------------------------------

### listfeatures with go run

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/client/listfeatures

Example of using listfeatures with a Go-based MCP server.

```bash
listfeatures go run github.com/modelcontextprotocol/go-sdk/examples/server/hello
```

--------------------------------

### Start the MCP Server

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/http

Starts an MCP server on the default address http://localhost:8000 providing the cityTime tool.

```bash
go run . server
```

--------------------------------

### Sampling output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for sampling.

```text
Output:
would have created a message
```

--------------------------------

### PromptContent output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for prompt content.

```text
Output:
user embedded resource: doc://style-guide (text/markdown)
user image: image/png, 8 bytes
user text: Review the screenshot against the style guide.
```

--------------------------------

### BinaryResource output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for a binary resource operation.

```text
Output:
file:///logo.png: 8 bytes of image/png, text is ""
```

--------------------------------

### Lifecycle output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for a lifecycle event.

```text
Output:
```

--------------------------------

### Logging output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for logging events.

```text
Output:
info shows up 1
warn shows up 3
```

--------------------------------

### ClientSession.GetPrompt

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets a prompt from the server.

```APIDOC
## ClientSession.GetPrompt

### Description
Gets a prompt from the server.

### Method
GetPrompt

### Signature
func (cs *ClientSession) GetPrompt(ctx context.Context, params *GetPromptParams) (*GetPromptResult, error)

### Parameters
- **ctx** (context.Context) - Required - The context for the call.
- **params** (*GetPromptParams) - Required - The parameters for the prompt request.

### Returns
- **result** (*GetPromptResult) - The prompt result.
- **error** (error) - An error if the call fails.
```

--------------------------------

### ResourceSubscription output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for resource subscription events.

```text
Output:
subscribed to config://app
re-read: theme=dark
unsubscribed from config://app
```

--------------------------------

### Persistence Example Output

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/auth

Shows the expected console output when implementing OAuth2 session persistence, demonstrating the flow of connecting, authorizing, and restoring a session.

```text
Output:
--- First connect ---
No session found to restore.
No token source found. Transport is calling Authorize()...
Saving token: mock-token
--- Second connect ---
Restoring session.
```

--------------------------------

### ClientSession.GetPrompt

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets a prompt from the MCP server.

```APIDOC
## GetPrompt

### Description
Retrieves a prompt from the MCP server using the provided parameters.

### Method
GetPrompt(ctx context.Context, params *GetPromptParams) (*GetPromptResult, error)

### Parameters
- **ctx** (context.Context) - Required - The context for the call.
- **params** (*GetPromptParams) - Required - The parameters for getting the prompt.

### Returns
- **result** (*GetPromptResult) - The prompt content.
- **err** (error) - An error if the call fails.
```

--------------------------------

### listfeatures with npx

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/client/listfeatures

Example of using listfeatures with a Node.js-based MCP server via npx.

```bash
listfeatures npx @modelcontextprotocol/server-everything
```

--------------------------------

### ElicitationComplete output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for a completed elicitation flow.

```text
Output:
opening https://calendar.example.com/consent?state=connect-calendar-1
flow finished: connect-calendar-1
```

--------------------------------

### FakeAuthorizationServer.Start

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/internal/oauthtest

Starts the HTTP server and registers a cleanup function on the testing.T to close the server when the test completes.

```APIDOC
## FakeAuthorizationServer.Start

### Description
Starts the HTTP server and registers a cleanup function on the testing.T to close the server when the test completes.

### Method
Start

### Parameters
- **t** (testing.TB) - Required - The testing object used for cleanup registration.
```

--------------------------------

### FakeIdPServer.Start

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/internal/oauthtest

Starts the HTTP server and registers a cleanup function on the testing.T to close the server when the test completes.

```APIDOC
## FakeIdPServer.Start

### Description
Starts the HTTP server and registers a cleanup function on the testing.T to close the server when the test completes.

### Method
Start

### Parameters
- **t** (testing.TB) - Required - The testing object used for cleanup registration.
```

--------------------------------

### Elicitation output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for an elicitation operation.

```text
Output:
value
```

--------------------------------

### Start Server on Custom Host and Port

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/http

Allows running the MCP server on a specific host and port using the -host and -port flags.

```bash
go run . -host 0.0.0.0 -port 9000 server
```

--------------------------------

### Cancellation output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output when a tool or context is canceled.

```text
Output:
context canceled
tool canceled
```

--------------------------------

### Create an alternative branch with continue_thinking

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Example JSON-RPC request to call the continue_thinking tool with the createBranch parameter to create an alternative reasoning path.

```json
{
  "method": "tools/call",
  "params": {
    "name": "continue_thinking",
    "arguments": {
      "sessionId": "architecture_design", 
      "thought": "Alternative approach: Start with a monolith-first strategy and extract services gradually.",
      "createBranch": true
    }
  }
}
```

--------------------------------

### ElicitationSchema output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for an elicitation schema operation.

```text
Output:
Exported as pdf
```

--------------------------------

### Run loadtest command

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/client/loadtest

Example usage of the loadtest command to test a specific tool with provided arguments against a local MCP server.

```bash
loadtest -tool=greet -args='{"name": "foo"}' http://localhost:8080
```

--------------------------------

### ListChanged output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for list changed notifications.

```text
Output:
changed: tools
changed: prompts
changed: resources
changed: tools
```

--------------------------------

### RootsListChanged output example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Displays the output for roots list changed events.

```text
Output:
file:///project
file:///scratch
roots changed again
```

--------------------------------

### Strict Byte-Equal Comparison for MatchesResource

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/oauthex

Example of how to perform a strict byte-equal comparison for claims as required by RFC 9728 §3.3.

```go
for _, c := range claims { if c == resource { return true } }
```

--------------------------------

### MCPGODEBUG environment variable format

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/internal/mcpgodebug

Example of the comma-separated key=value pair format used for the MCPGODEBUG environment variable.

```text
MCPGODEBUG=someoption=1,otheroption=value
```

--------------------------------

### Create and run an MCP server with a tool

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk

Demonstrates initializing an mcp.Server, registering a tool using mcp.AddTool, and running the server over an mcp.StdioTransport.

```go
package main

import (
	"context"
	"log"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

type Input struct {
	Name string `json:"name" jsonschema:"the name of the person to greet"`
}

type Output struct {
	Greeting string `json:"greeting" jsonschema:"the greeting to tell to the user"`
}

func SayHi(ctx context.Context, req *mcp.CallToolRequest, input Input) (
	*mcp.CallToolResult,
	Output,
	error,
) {
	return nil, Output{Greeting: "Hi " + input.Name}, nil
}

func main() {
	// Create a server with a single tool.
	server := mcp.NewServer(&mcp.Implementation{Name: "greeter", Version: "v1.0.0"}, nil)
	mcp.AddTool(server, &mcp.Tool{Name: "greet", Description: "say hi"}, SayHi)
	// Run the server over stdin/stdout, until the client disconnects.
	if err := server.Run(context.Background(), &mcp.StdioTransport{}); err != nil {
		log.Fatal(err)
	}
}
```

--------------------------------

### Run the server in HTTP mode

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Starts the sequential thinking MCP server with HTTP transport on port 8080. Use the -http flag to enable HTTP mode.

```bash
go run . -http :8080
```

--------------------------------

### Complete the thinking process with continue_thinking

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/server/sequentialthinking

Example JSON-RPC request to call the continue_thinking tool with nextNeeded set to false to indicate the thinking process is complete.

```json
{
  "method": "tools/call",
  "params": {
    "name": "continue_thinking",
    "arguments": {
      "sessionId": "architecture_design",
      "thought": "Based on this analysis, I recommend starting with 3 core services: User Management, Order Processing, and Inventory Management.",
      "nextNeeded": false
    }
  }
}
```

--------------------------------

### Connect to an MCP server and call a tool

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk

Shows how to initialize an mcp.Client, connect to a server using mcp.CommandTransport, and invoke a tool via session.CallTool.

```go
package main

import (
	"context"
	"log"
	"os/exec"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

func main() {
	ctx := context.Background()

	// Create a new client, with no features.
	client := mcp.NewClient(&mcp.Implementation{Name: "mcp-client", Version: "v1.0.0"}, nil)

	// Connect to a server over stdin/stdout.
	transport := &mcp.CommandTransport{Command: exec.Command("myserver")}
	session, err := client.Connect(ctx, transport, nil)
	if err != nil {
		log.Fatal(err)
	}
	defer session.Close()

	// Call a tool on the server.
	params := &mcp.CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "you"},
	}
	res, err := session.CallTool(ctx, params)
	if err != nil {
		log.Fatalf("CallTool failed: %v", err)
	}
	if res.IsError {
		log.Fatal("tool failed")
	}
	for _, c := range res.Content {
		log.Print(c.(*mcp.TextContent).Text)
	}
}
```

--------------------------------

### Connect to the server using CommandTransport

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Creates a client and connects to the server via CommandTransport, then calls the greet tool with a name argument. Logs fatal errors if connection or call fails.

```go
client := mcp.NewClient(&mcp.Implementation{Name: "mcp-client", Version: "v1.0.0"}, nil)
transport := &mcp.CommandTransport{Command: exec.Command("myserver")}
session, err := client.Connect(ctx, transport, nil)
if err != nil {
	log.Fatal(err)
}
defer session.Close()

params := &mcp.CallToolParams{
	Name:      "greet",
	Arguments: map[string]any{"name": "you"},
}
res, err := session.CallTool(ctx, params)
if err != nil {
	log.Fatalf("CallTool failed: %v", err)
}

```

--------------------------------

### Run a simple server on StdioTransport

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Creates a server with the generic AddTool, which automatically populates the tool's input and output schema. The server runs on the StdioTransport and logs an error if it fails.

```go
server := mcp.NewServer(&mcp.Implementation{Name: "greeter"}, nil)

// Using the generic AddTool automatically populates the the input and output
// schema of the tool.
type args struct {
	Name string `json:"name" jsonschema:"the person to greet"`
}
mcp.AddTool(server, &mcp.Tool{
	Name:        "greet",
	Description: "say hi",
}, func(ctx context.Context, req *mcp.CallToolRequest, args args) (*mcp.CallToolResult, any, error) {
	return &mcp.CallToolResult{
		Content: []mcp.Content{
			&mcp.TextContent{Text: "Hi " + args.Name},
		},
	}, nil, nil
})

// Run the server on the stdio transport.
if err := server.Run(context.Background(), &mcp.StdioTransport{}); err != nil {
	log.Printf("Server failed: %v", err)
}

```

--------------------------------

### StreamableHTTPHandler Example Output

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Example output from a StreamableHTTPHandler test showing a JSON-RPC response with capabilities, protocol version, and server info.

```json
{"jsonrpc":"2.0","id":1,"result":{"capabilities":{"logging":{}},"protocolVersion":"2025-11-25","serverInfo":{"name":"server","version":"v0.1.0"}}}

```

--------------------------------

### Claude Code Interaction Example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/http

Example of querying the timezone tool and receiving responses from the MCP server within the Claude Code interface.

```text
> what's the timezone

⏺ I'll get the current time in a major US city for you.

⏺ timezone - cityTime (MCP)(city: "nyc")
  ⎿ The current time in New York City is 7:30:16 PM EDT on Wedn
    esday, July 23, 2025


⏺ The current timezone is EDT (Eastern Daylight Time), and it's
   7:30 PM on Wednesday, July 23, 2025.

> what timezones do you support?

⏺ The timezone tool supports three US cities:
  - NYC (Eastern Time)
  - SF (Pacific Time)
  - Boston (Eastern Time)
```

--------------------------------

### ClientRequest.GetParams

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the request parameters.

```APIDOC
## ClientRequest.GetParams

### Description
Gets the request parameters.

### Method
GetParams() Params

### Returns
- **params** (Params) - The request parameters.
```

--------------------------------

### ElicitParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from ElicitParams.

```APIDOC
## ElicitParams.GetProgressToken

### Description
Gets the progress token from ElicitParams.

### Method
GetProgressToken

### Signature
func (x *ElicitParams) GetProgressToken() any

### Returns
- (any) - The progress token.
```

--------------------------------

### DiscoverParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from DiscoverParams.

```APIDOC
## DiscoverParams.GetProgressToken

### Description
Gets the progress token from DiscoverParams.

### Method
GetProgressToken

### Signature
func (x *DiscoverParams) GetProgressToken() any

### Returns
- (any) - The progress token.
```

--------------------------------

### ToolListChangedParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from ToolListChangedParams.

```APIDOC
## ToolListChangedParams.GetProgressToken

### Description
Gets the progress token from ToolListChangedParams.

### Method
GetProgressToken

### Signature
func (x *ToolListChangedParams) GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### ElicitParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from ElicitParams.

```APIDOC
## ElicitParams.GetProgressToken

### Description
Gets the progress token from ElicitParams.

### Method
GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### DiscoverParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from DiscoverParams.

```APIDOC
## DiscoverParams.GetProgressToken

### Description
Gets the progress token from DiscoverParams.

### Method
GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### ClientRequest.GetSession

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the session associated with the request.

```APIDOC
## ClientRequest.GetSession

### Description
Gets the session associated with the request.

### Method
GetSession() Session

### Returns
- **session** (Session) - The session.
```

--------------------------------

### ClientRequest.GetExtra

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the extra request data.

```APIDOC
## ClientRequest.GetExtra

### Description
Gets the extra request data.

### Method
GetExtra() *RequestExtra

### Returns
- **extra** (*RequestExtra) - The extra request data.
```

--------------------------------

### NewClient

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Creates a new Client instance.

```APIDOC
## NewClient

### Description
Creates a new Client instance with the given implementation and options.

### Method
NewClient(impl *Implementation, options *ClientOptions) *Client

### Parameters
- **impl** (*Implementation) - Required - The implementation information.
- **options** (*ClientOptions) - Optional - Options for the client.

### Returns
- **client** (*Client) - The new client.
```

--------------------------------

### CancelledParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from CancelledParams.

```APIDOC
## CancelledParams.GetProgressToken

### Description
Gets the progress token from CancelledParams.

### Method
GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### type ServerOptions

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Configuration options for creating a server. Includes optional instructions, logger, handlers for various notifications, pagination settings, keepalive configuration, and resource subscription handlers.

```APIDOC
## type ServerOptions

### Description
ServerOptions configures the behavior of a server. It includes optional instructions for connected clients, a logger, handlers for various notifications, pagination settings, keepalive configuration, and resource subscription handlers.

### Fields
- **Instructions** (string) - Optional instructions for connected clients.
- **Logger** (*slog.Logger) - Optional logger to enable logging of server activity.
- **InitializedHandler** (func(context.Context, *InitializedRequest)) - Optional handler called when "notifications/initialized" is received.
- **PageSize** (int) - Maximum number of items to return in a single page for list methods (e.g. ListTools). If zero, defaults to DefaultPageSize.
- **RootsListChangedHandler** (func(context.Context, *RootsListChangedRequest)) - Optional handler called when "notifications/roots/list_changed" is received. Deprecated as of protocol version 2026-07-28 (SEP-2577).
- **ProgressNotificationHandler** (func(context.Context, *ProgressNotificationServerRequest)) - Optional handler called when "notifications/progress" is received.
- **CompletionHandler** (func(context.Context, *CompleteRequest) (*CompleteResult, error)) - Optional handler called when "completion/complete" is received.
- **KeepAlive** (time.Duration) - If non-zero, defines an interval for regular "ping" requests. If the peer fails to respond, the session is automatically closed.
- **KeepAliveFailureThreshold** (int) - Number of consecutive keepalive ping failures tolerated before the session is closed. A value of 0 or 1 closes on the first failure (default). Has no effect unless KeepAlive is non-zero.
- **SubscribeHandler** (func(context.Context, *SubscribeRequest) error) - Function called when a client session subscribes to a resource.
- **UnsubscribeHandler** (func(context.Context, *UnsubscribeRequest) error) - Function called when a client session unsubscribes from a resource.
```

--------------------------------

### NewServer

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Creates a new MCP server instance with the given implementation and options.

```APIDOC
## NewServer

### Description
Creates a new MCP server instance with the given implementation and options.

### Method
func NewServer(impl *Implementation, options *ServerOptions) *Server

### Parameters
- **impl** (*Implementation) - Required - The server implementation information.
- **options** (*ServerOptions) - Required - Configuration options for the server.

### Returns
- **server** (*Server) - The newly created server instance.
```

--------------------------------

### CreateMessageWithToolsParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from CreateMessageWithToolsParams (deprecated).

```APIDOC
## CreateMessageWithToolsParams.GetProgressToken

### Description
Gets the progress token from CreateMessageWithToolsParams. This method is deprecated.

### Method
GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### CreateMessageParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from CreateMessageParams (deprecated).

```APIDOC
## CreateMessageParams.GetProgressToken

### Description
Gets the progress token from CreateMessageParams. This method is deprecated.

### Method
GetProgressToken() any

### Returns
- **token** (any) - The progress token.
```

--------------------------------

### type ClientOptions

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Options for configuring a Client instance.

```APIDOC
## type ClientOptions

### Description
Options for configuring a Client instance.

### Fields
No fields are documented in the provided source.
```

--------------------------------

### ParamsBase struct and SearchParams embedding example

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

ParamsBase can be embedded in custom parameter structs to satisfy the Params interface. It provides the required Meta field and the unexported isParams marker method. The SearchParams example shows embedding mcp.ParamsBase and adding a Query field.

```go
type ParamsBase struct {
	Meta `json:"_meta,omitempty"`
}
```

```go
type SearchParams struct {
    mcp.ParamsBase
    Query string `json:"query"`
}
```

--------------------------------

### NewClient

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

NewClient creates a new Client. Use Client.Connect to connect it to an MCP server. The first argument must not be nil. If non-nil, the provided options configure the Client.

```APIDOC
## NewClient

### Description
NewClient creates a new Client. Use Client.Connect to connect it to an MCP server. The first argument must not be nil. If non-nil, the provided options configure the Client.

### Method
func NewClient(impl *Implementation, options *ClientOptions) *Client

### Parameters
- **impl** (*Implementation) - Required - The implementation information for the client.
- **options** (*ClientOptions) - Optional - Configuration options for the client.

### Return Value
- **Client** - A new Client instance.
```

--------------------------------

### ClientSession.Complete

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Completes a prompt or resource reference on the MCP server.

```APIDOC
## Complete

### Description
Completes a prompt or resource reference on the MCP server.

### Method
Complete(ctx context.Context, params *CompleteParams) (*CompleteResult, error)

### Parameters
- **ctx** (context.Context) - Required - The context for the call.
- **params** (*CompleteParams) - Required - The parameters for the completion.

### Returns
- **result** (*CompleteResult) - The completion result.
- **err** (error) - An error if the call fails.
```

--------------------------------

### type GetPromptParams

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

GetPromptParams contains parameters for getting a prompt.

```APIDOC
## Type: GetPromptParams

### Description
GetPromptParams contains parameters for getting a prompt.

### Fields
- **Meta** (Meta) - json:"_meta,omitempty" - Reserved by the protocol to allow clients and servers to attach additional metadata to their responses.
- **Arguments** (map[string]string) - json:"arguments,omitempty" - Arguments to use for templating the prompt.
- **Name** (string) - json:"name" - The name of the prompt or prompt template.

```

--------------------------------

### SetLoggingLevelParams.GetProgressToken

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Gets the progress token from the SetLoggingLevelParams. This method is deprecated.

```APIDOC
## SetLoggingLevelParams.GetProgressToken

### Description
Gets the progress token from the SetLoggingLevelParams. This method is deprecated.

### Method
GetProgressToken

### Signature
func (x *SetLoggingLevelParams) GetProgressToken() any

### Returns
- **token** (any) - The progress token.

### Deprecated
This method is deprecated.
```

--------------------------------

### ClientSession.ListPrompts

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Lists the prompts available on the MCP server.

```APIDOC
## ListPrompts

### Description
Retrieves a list of prompts available on the MCP server.

### Method
ListPrompts(ctx context.Context, params *ListPromptsParams) (*ListPromptsResult, error)

### Parameters
- **ctx** (context.Context) - Required - The context for the call.
- **params** (*ListPromptsParams) - Required - The parameters for listing prompts.

### Returns
- **result** (*ListPromptsResult) - The list of prompts.
- **err** (error) - An error if the call fails.
```

--------------------------------

### ClientSession.InitializeResult

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Returns the initialization result from the MCP server.

```APIDOC
## InitializeResult

### Description
Returns the initialization result received from the MCP server.

### Method
InitializeResult() *InitializeResult

### Returns
- **result** (*InitializeResult) - The initialization result.
```

--------------------------------

### Run the MCP Client

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/examples/http

Connects to the running server, lists available tools, and executes the cityTime tool for specified cities.

```bash
go run . client
```

--------------------------------

### DefaultPageSize constant

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Default for ServerOptions.PageSize.

```go
const DefaultPageSize = 1000
```

--------------------------------

### func (*Client) Connect

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Begins an MCP session by connecting to a server over the given transport. The resulting session is initialized and ready to use.

```APIDOC
## func (*Client) Connect

### Description
Connect begins an MCP session by connecting to a server over the given transport. The resulting session is initialized, and ready to use. Typically, it is the responsibility of the client to close the connection when it is no longer needed. However, if the connection is closed by the server, calls or notifications will return an error wrapping ErrConnectionClosed.

### Method
Connect

### Endpoint
Client.Connect

### Parameters
#### Function Parameters
- **ctx** (context.Context) - Required - The context for the connection.
- **t** (Transport) - Required - The transport to connect over.
- **opts** (*ClientSessionOptions) - Optional - Session options.

### Response
#### Success Response
- **cs** (*ClientSession) - The initialized client session.
- **err** (error) - An error if the connection fails.
```

--------------------------------

### ClientSession.ListTools

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

Lists the tools available on the MCP server.

```APIDOC
## ListTools

### Description
Retrieves a list of tools available on the MCP server.

### Method
ListTools(ctx context.Context, params *ListToolsParams) (*ListToolsResult, error)

### Parameters
- **ctx** (context.Context) - Required - The context for the call.
- **params** (*ListToolsParams) - Required - The parameters for listing tools.

### Returns
- **result** (*ListToolsResult) - The list of tools.
- **err** (error) - An error if the call fails.
```

--------------------------------

### NewServer

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp

NewServer creates a new Server instance with the given implementation and options.

```APIDOC
## NewServer

### Description
NewServer creates a new Server instance with the given implementation and options.

### Method
func NewServer(impl *Implementation, options *ServerOptions) *Server

### Parameters
- **impl** (*Implementation) - Required - The implementation details for the server.
- **options** (*ServerOptions) - Required - The server options.

### Returns
- ***Server** - A new Server instance.
```

--------------------------------

### Async

Source: https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/internal/jsonrpc2

Starts an asynchronous operation in the background. This function is used to run a goroutine that will be managed by the connection.

```APIDOC
## Async

### Description
Starts an asynchronous operation in the background. This function is used to run a goroutine that will be managed by the connection.

### Function Signature
func Async(ctx context.Context)

### Parameters
- ctx (context.Context) - Required - The context for the asynchronous operation.
```
Tokens:
Raw