riza-io/mcp-go

==========
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 that
exposes the contents of an io.FS as resources.
go
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{