Go MCP SDK: Complete Developer Guide

Overview

The Go MCP SDK is the official library for building MCP servers in Go. It supports tools, resources, prompts, transports, and the stdio and streamable-http transport.

Installation

go get github.com/modelcontextprotocol/go-sdk

Minimal Server Example

server := mcp.NewServer("my-server", "1.0.0")

server.AddTool(mcp.Tool{
    Name:        "add",
    Description: "Add two numbers",
    InputSchema: mcp.ToolInputSchema{
        Type: "object",
        Properties: map[string]any{
            "a": map[string]any{"type": "number"},
            "b": map[string]any{"type": "number"},
        },
    },
}, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
    a := req.Params.Arguments["a"].(float64)
    b := req.Params.Arguments["b"].(float64)
    return mcp.NewToolResultText(fmt.Sprintf("%v", a+b)), nil
})

Adding a Tool

Tools are the primary way MCP servers expose functionality to clients. Each tool has a name, input schema, and handler function.

// Add more tools with server.AddTool(...)

Supported Features

Testing Your Server

1. Start the server and verify it prints no startup errors.
2. Run npx @modelcontextprotocol/inspector and connect over stdio.
3. Call your tools and verify they return the expected responses.
4. Connect from Claude Desktop and confirm tool visibility.