Yet Another MCP Library for Go

[Warashi]

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I recently published yet another MCP Library for Go, Warashi/go-modelcontextprotocol.

This package has no 3rd-party dependencies.
I have implemented resources and tools features of protocol version 2024-11-05, and I'm planning to implement latest version, 2025-03-26.

Here's a simple example of creating an MCP server with a tool

package main

import (
	"context"
	"log"

	"github.com/Warashi/go-modelcontextprotocol/jsonschema"
	"github.com/Warashi/go-modelcontextprotocol/mcp"
)

// Define types for request and response
type GreetRequest struct {
	Name string `json:"name" jsonschema:"required,description=The name of the person to greet"`
}

type GreetResponse struct {
	Greeting string `json:"greeting"`
}

func main() {
	// Create a schema from the request type
	schema, err := jsonschema.FromStruct(GreetRequest{})
	if err != nil {
		log.Fatalf("Failed to create schema: %v", err)
	}

	// or you can create a schema with jsonschema.Object{}
	// schema = jsonschema.Object{
	// 	Properties: map[string]jsonschema.Schema{
	// 		"name": jsonschema.String{
	// 			Description: "The name of the person to greet",
	// 		},
	// 	},
	// 	Required: []string{"name"},
	// }

	// Create a tool
	tool := mcp.NewToolFunc(
		"greet",
		"Greets a person by name",
		schema,
		func(ctx context.Context, input GreetRequest) (GreetResponse, error) {
			return GreetResponse{
				Greeting: "Hello, " + input.Name + "!",
			}, nil
		},
	)

	// Create a server with the tool
	server, err := mcp.NewServer("example", "1.0.0", mcp.WithTool(tool))
	if err != nil {
		log.Fatalf("Failed to create server: %v", err)
	}

	// Serve the server over stdin/stdout
	ctx := context.Background()
	if err := server.ServeStdio(ctx); err != nil {
		log.Fatalf("Server failed: %v", err)
	}
}

Relevant Links

GitHub: https://github.com/Warashi/go-modelcontextprotocol

The server implementations using this library:

• mcp-server-pipecd - An MCP server for PipeCD integration

[VishalMCF]

I have forked it bro. Will dissect it today