Write tools for LLMs with go - mcp-golang

We just open-sourced mcp-golang!

A few weeks ago, Anthropic released Model Context Protocol - a protocol to allow LLMs to use tools and interact with the world.

The base sdks written by Anthropic were for Typescript and python, so if you wanted to use go, you were out of luck.

With mcp-golang you can now write tool servers in just a few lines of code in go.

The server below allows an LLM to understand the weather in any location.

package main

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

type WeatherArguments struct {
    Longitude float64 `json:"longitude" jsonschema:"required,description=The longitude of the location to get the weather for"`
    Latitude  float64 `json:"latitude" jsonschema:"required,description=The latitude of the location to get the weather for"`
}

// This is explained in the docs at https://mcpgolang.com/tools
func main() {
    done := make(chan struct{})
    server := mcp_golang.NewServer(stdio.NewStdioServerTransport())
    err := server.RegisterTool("get_weather", "Get the weather forecast for temperature, wind speed and relative humidity", func(arguments WeatherArguments) (*mcp_golang.ToolResponse, error) {
        url := fmt.Sprintf("https://api.open-meteo.com/v1/forecast?latitude=%f&longitude=%f&current=temperature_2m,wind_speed_10m&hourly=temperature_2m,relative_humidity_2m,wind_speed_10m", arguments.Latitude, arguments.Longitude)
        resp, err := http.Get(url)
        if err != nil {
            return nil, err
        }
        defer resp.Body.Close()
        output, err := io.ReadAll(resp.Body)
        if err != nil {
            return nil, err
        }
        return mcp_golang.NewToolReponse(mcp_golang.NewTextContent(string(output))), nil
    })
    err = server.Serve()
    if err != nil {
        panic(err)
    }
    <-done
}

Check out a demo at https://www.youtube.com/watch?v=xaMkMl_R-0A! And the github repo at https://github.com/metoro-io/mcp-golang

Happy coding!