mcp-go

Overview

mcp-go is a Go SDK for building Model Context Protocol servers and clients. It provides high-level APIs for defining tools, resources, prompts, request handlers, transports, sessions, hooks, task-augmented tools, sampling, roots, validation, and tracing.

Use it when a Go service needs to expose data or actions to Claude, Cursor, Codex, VS Code, custom MCP hosts, or another MCP-compatible client without hand-rolling the JSON-RPC protocol layer.

Core Capabilities

Quick Start

Install the module:

go get github.com/mark3labs/mcp-go

A minimal stdio server defines a tool and handler:

package main

import (
    "context"
    "fmt"

    "github.com/mark3labs/mcp-go/mcp"
    "github.com/mark3labs/mcp-go/server"
)

func main() {
    s := server.NewMCPServer(
        "Demo",
        "1.0.0",
        server.WithToolCapabilities(false),
    )

    tool := mcp.NewTool("hello_world",
        mcp.WithDescription("Say hello to someone"),
        mcp.WithString("name", mcp.Required()),
    )

    s.AddTool(tool, func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
        name, err := request.RequireString("name")
        if err != nil {
            return mcp.NewToolResultError(err.Error()), nil
        }
        return mcp.NewToolResultText(fmt.Sprintf("Hello, %s!", name)), nil
    })

    if err := server.ServeStdio(s); err != nil {
        panic(err)
    }
}

MCP Fit

Go teams can use mcp-go to expose existing service logic as MCP tools, resources, and prompts while keeping protocol handling in a library. The same server can start as a local stdio integration for desktop clients and later move to Streamable HTTP or SSE when a hosted boundary is needed.

Because MCP tools are action surfaces, treat each handler with the same rigor as an internal API endpoint: validation, authorization, observability, and clear side-effect boundaries matter.

Use Cases

• Build a Go MCP server around internal APIs, CLIs, databases, or developer tools.
• Expose structured resources from a Go service to MCP-compatible clients.
• Add MCP support to an existing Go daemon or developer platform.
• Prototype stdio MCP servers before deploying a network transport.
• Use testing helpers and validation to keep tool schemas stable.

Source Review

Verified on 2026-06-18:

• The upstream README describes mcp-go as a Go implementation of the Model Context Protocol with tools, resources, prompts, transports, session management, hooks, OAuth protected-resource metadata, and code generation notes.
• go.mod declares the module path github.com/mark3labs/mcp-go and current Go/dependency requirements.
• GitHub reports MIT licensing and active development for mark3labs/mcp-go.
• pkg.go.dev resolves package documentation for github.com/mark3labs/mcp-go.

Safety and Privacy

mcp-go itself is a library. The sensitive part is the server you build with it. Keep tool handlers narrow, validate all arguments, avoid broad filesystem or network access by default, and add explicit authentication before exposing HTTP/SSE transports outside localhost.

Be careful with generated tool descriptions and error messages: they become model-visible context. Avoid leaking secrets, internal identifiers, private paths, customer records, or privileged operational details through schemas, logs, traces, or validation errors.

Duplicate Check

Checked current content/mcp/, content/tools/, content/skills/, open pull requests, and repository-wide content for mark3labs/mcp-go, mcp-go, Go MCP SDK, Golang MCP server, Model Context Protocol Go, Go MCP client, Streamable HTTP MCP Go, and MCP tools Go. No dedicated mcp-go entry, exact source URL duplicate, target file, or open duplicate PR was found.