README
¶
MCP Go 🚀
A Go implementation of the Model Context Protocol (MCP), enabling seamless integration between LLM applications and external data sources and tools.
package main
import (
"context"
"fmt"
"github.com/mark3labs/mcp-go/mcp"
"github.com/mark3labs/mcp-go/server"
)
func main() {
// Create MCP server
s := server.NewMCPServer(
"Demo 🚀",
"1.0.0",
server.WithToolCapabilities(true),
)
// Add tool
tool := mcp.NewTool("hello_world",
mcp.WithDescription("Say hello to someone"),
mcp.WithString("name",
mcp.Required(),
mcp.Description("Name of the person to greet"),
),
)
// Add tool handler
s.AddTool(tool, helloHandler)
// Start the stdio server
if err := server.ServeStdio(s); err != nil {
fmt.Printf("Server error: %v\n", err)
}
}
func helloHandler(ctx context.Context, arguments map[string]interface{}) (*mcp.CallToolResult, error) {
name, ok := arguments["name"].(string)
if !ok {
return mcp.NewToolResultError("name must be a string"), nil
}
return mcp.NewToolResultText(fmt.Sprintf("Hello, %s!", name)), nil
}
That's it!
MCP Go handles all the complex protocol details and server management, so you can focus on building great tools. It aims to be high-level and easy to use.
Key features:
- Fast: High-level interface means less code and faster development
- Simple: Build MCP servers with minimal boilerplate
- Complete*: MCP Go aims to provide a full implementation of the core MCP specification
(*emphasis on aims)
🚨 🚧 🏗️ MCP Go is under active development, as is the MCP specification itself. Core features are working but some advanced capabilities are still in progress.
Table of Contents
Installation
go get github.com/mark3labs/mcp-go
Quickstart
Let's create a simple MCP server that exposes a calculator tool and some data:
// TODO
What is MCP?
The Model Context Protocol (MCP) lets you build servers that expose data and functionality to LLM applications in a secure, standardized way. Think of it like a web API, but specifically designed for LLM interactions. MCP servers can:
- Expose data through Resources (think of these sort of like GET endpoints; they are used to load information into the LLM's context)
- Provide functionality through Tools (sort of like POST endpoints; they are used to execute code or otherwise produce a side effect)
- Define interaction patterns through Prompts (reusable templates for LLM interactions)
- And more!
Core Concepts
Server
The server is your core interface to the MCP protocol. It handles connection management, protocol compliance, and message routing:
// TODO
Resources
Resources are how you expose data to LLMs. They're similar to GET endpoints in a REST API - they provide data but shouldn't perform significant computation or have side effects. Some examples:
- File contents
- Database schemas
- API responses
- System information
Resources can be static:
// TODO
Tools
Tools let LLMs take actions through your server. Unlike resources, tools are expected to perform computation and have side effects. They're similar to POST endpoints in a REST API.
Simple calculation example:
// TODO
HTTP request example:
// TODO
Prompts
Prompts are reusable templates that help LLMs interact with your server effectively. They're like "best practices" encoded into your server. A prompt can be as simple as a string:
// TODO
Or a more structured sequence of messages:
// TODO
Examples
For examples, see the examples/ directory.
Contributing
Open Developer Guide
Prerequisites
Go version >= 1.23
Installation
Create a fork of this repository, then clone it:
git clone https://github.com/mark3labs/mcp-go.git
cd mcp-go
Testing
Please make sure to test any new functionality. Your tests should be simple and atomic and anticipate change rather than cement complex patterns.
Run tests from the root directory:
go test -v './...'
Opening a Pull Request
Fork the repository and create a new branch:
git checkout -b my-branch
Make your changes and commit them:
git add . && git commit -m "My changes"
Push your changes to your fork:
git push origin my-branch
Feel free to reach out in a GitHub issue or discussion if you have any questions!
Directories