riza-io

MCP Go SDK

Community riza-io
Updated

Build Model Context Protocol (MCP) servers in Go

MCP Go SDK

BuildGo Report CardGoDoc

A Go implementation of the Model Context Protocol (MCP), providing both client and server capabilities for integrating with LLM surfaces.

Overview

The Model Context Protocol allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction. This Go SDK implements the full MCP specification, making it easy to:

  • Build MCP clients that can connect to any MCP server
  • Create MCP servers that expose resources, prompts and tools
  • Use standard transports like stdio and SSE (coming soon)
  • Handle all MCP protocol messages and lifecycle events

A small example

Curious what all this looks like in practice? Here's an example server thatexposes the contents of an io.FS as resources.

package main

import (
	"context"
	"flag"
	"io/fs"
	"log"
	"mime"
	"os"
	"path/filepath"
	"strings"

	"github.com/riza-io/mcp-go"
)

type FSServer struct {
	fs fs.FS

	mcp.UnimplementedServer
}

func (s *FSServer) Initialize(ctx context.Context, req *mcp.Request[mcp.InitializeRequest]) (*mcp.Response[mcp.InitializeResponse], error) {
	return mcp.NewResponse(&mcp.InitializeResponse{
		ProtocolVersion: req.Params.ProtocolVersion,
		Capabilities: mcp.ServerCapabilities{
			Resources: &mcp.Resources{},
		},
	}), nil
}

func (s *FSServer) ListResources(ctx context.Context, req *mcp.Request[mcp.ListResourcesRequest]) (*mcp.Response[mcp.ListResourcesResponse], error) {
	var resources []mcp.Resource
	fs.WalkDir(s.fs, ".", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			return nil
		}
		resources = append(resources, mcp.Resource{
			URI:      "file://" + path,
			Name:     path,
			MimeType: mime.TypeByExtension(filepath.Ext(path)),
		})
		return nil
	})
	return mcp.NewResponse(&mcp.ListResourcesResponse{
		Resources: resources,
	}), nil
}

func (s *FSServer) ReadResource(ctx context.Context, req *mcp.Request[mcp.ReadResourceRequest]) (*mcp.Response[mcp.ReadResourceResponse], error) {
	contents, err := fs.ReadFile(s.fs, strings.TrimPrefix(req.Params.URI, "file://"))
	if err != nil {
		return nil, err
	}
	return mcp.NewResponse(&mcp.ReadResourceResponse{
		Contents: []mcp.ResourceContent{
			{
				URI:      req.Params.URI,
				MimeType: mime.TypeByExtension(filepath.Ext(req.Params.URI)),
				Text:     string(contents), // TODO: base64 encode
			},
		},
	}), nil
}

func main() {
	flag.Parse()

	root := flag.Arg(0)
	if root == "" {
		root = "/"
	}

	server := mcp.NewStdioServer(&FSServer{
		fs: os.DirFS(root),
	})

	if err := server.Listen(context.Background(), os.Stdin, os.Stdout); err != nil {
		log.Fatal(err)
	}
}

You can compile this example and wire it up to Claude Desktop (or any other MCP client).

{
	"mcpServers": {
		"fs": {
			"command": "/path/to/mcp-go-fs",
			"args": [
				"/path/to/root/directory"
			]
		}
	}
}

Documentation

Roadmap

The majority of the base protocol is implemented. The following features are on our roadmap:

  • Notifications
  • Sampling
  • Roots

Legal

Offered under the MIT license.

MCP Server ยท Populars

MCP Server ยท New

    browser-use

    Enable AI to control your browser ๐Ÿค–

    ๐ŸŒ Make websites accessible for AI agents. Automate tasks online with ease.

    Community browser-use
    superglue-ai

    superglue

    superglue integrates & orchestrates APIs from natural language. Agents use it to build deterministic workflows across apps, APIs and databases. Humans use it to generate insights, build automations and manage data.

    Community superglue-ai
    superglue-ai

    docs

    superglue integrates & orchestrates APIs from natural language. Agents use it to build deterministic workflows across apps, APIs and databases. Humans use it to generate insights, build automations and manage data.

    Community superglue-ai
    KemingHe

    Python Dependency Manager Companion MCP Server

    Self-updating MCP server to cross-reference latest official pip, poetry, uv, and conda docs

    Community KemingHe
    apache

    ECharts MCP

    Apache ECharts MCP Server

    Community apache