Quick Start

1. Installation
2. Getting started

Installation

go get github.com/modelcontextprotocol/go-sdk

Getting started

To get started creating an MCP server, create an mcp.Server instance, add features to it, and then run it over an mcp.Transport. For example, this server adds a single simple tool, and then connects it to clients over stdin/stdout:

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)
    }
}

To communicate with that server, create an mcp.Client and connect it to the corresponding server, by running the server command and communicating over its stdin/stdout:

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)
    }
}

The examples/ directory contains more example clients and servers.