mcp-golang

mcp-golang is an unofficial implementation of the Model Context Protocol in Go.

Write MCP servers and clients in golang with a few lines of code.

Docs at https://mcpgolang.com

Highlights

• 🛡️Type safety - Define your tool arguments as native go structs, have mcp-golang handle the rest. Automatic schema generation, deserialization, error handling etc.
• 🚛 Custom transports - Use the built-in transports (stdio for full feature support, HTTP for stateless communication) or write your own.
• ⚡ Low boilerplate - mcp-golang generates all the MCP endpoints for you apart from your tools, prompts and resources.
• 🧩 Modular - The library is split into three components: transport, protocol and server/client. Use them all or take what you need.
• 🔄 Bi-directional - Full support for both server and client implementations through stdio transport.

Example Usage

Install with go get github.com/metoro-io/mcp-golang

Server Example

package main

import (
    "fmt"
    "github.com/metoro-io/mcp-golang"
    "github.com/metoro-io/mcp-golang/transport/stdio"
)

// Tool arguments are just structs, annotated with jsonschema tags
// More at https://mcpgolang.com/tools#schema-generation
type Content struct {
    Title       string  `json:"title" jsonschema:"required,description=The title to submit"`
    Description *string `json:"description" jsonschema:"description=The description to submit"`
}
type MyFunctionsArguments struct {
    Submitter string  `json:"submitter" jsonschema:"required,description=The name of the thing calling this tool (openai, google, claude, etc)"`
    Content   Content `json:"content" jsonschema:"required,description=The content of the message"`
}

func main() {
    done := make(chan struct{})

    server := mcp_golang.NewServer(stdio.NewStdioServerTransport())
    err := server.RegisterTool("hello", "Say hello to a person", func(arguments MyFunctionsArguments) (*mcp_golang.ToolResponse, error) {
        return mcp_golang.NewToolResponse(mcp_golang.NewTextContent(fmt.Sprintf("Hello, %server!", arguments.Submitter))), nil
    })
    if err != nil {
        panic(err)
    }

    err = server.RegisterPrompt("promt_test", "This is a test prompt", func(arguments Content) (*mcp_golang.PromptResponse, error) {
        return mcp_golang.NewPromptResponse("description", mcp_golang.NewPromptMessage(mcp_golang.NewTextContent(fmt.Sprintf("Hello, %server!", arguments.Title)), mcp_golang.RoleUser)), nil
    })
    if err != nil {
        panic(err)
    }

    err = server.RegisterResource("test://resource", "resource_test", "This is a test resource", "application/json", func() (*mcp_golang.ResourceResponse, error) {
        return mcp_golang.NewResourceResponse(mcp_golang.NewTextEmbeddedResource("test://resource", "This is a test resource", "application/json")), nil
    })

    err = server.Serve()
    if err != nil {
        panic(err)
    }