mcp-go Go搭建MCP服务的实现示例

go get "github.com/mark3labs/mcp-go"

//新建mcp 服务
mcpServer := server.NewMCPServer("ziyi Mcp Server", "1.0.0")
//对外提供 stdio mcp server服务
if err := server.ServeStdio(mcpServer); err != nil {
	panic(err)
}

//新增一个mcp server对外暴露的静态资源（固定URI），比如：对外暴露项目的操作手册以及部署方式等，就可以通过静态资源README文件的方式来告诉大模型
resource := mcp.NewResource(
	"docs://readme",
	"项目的README文件",
	mcp.WithResourceDescription("这是一个项目的README文件"),
	mcp.WithMIMEType("text/markdown"),
)
// 添加对静态资源的处理器
mcpServer.AddResource(resource, func(ctx context.Context, request mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
	content, err := os.ReadFile("README.md")
	if err != nil {
		return nil, err
	}

	return []mcp.ResourceContents{
		mcp.TextResourceContents{
			URI:      "docs://readme",
			MIMEType: "text/markdown",
			Text:     string(content),
		},
	}, nil
})

//给该mcp server添加计算能力(Tools)
// 1. 描述该工具，以及调用该工具调用的参数机器含义
calculatorTool := mcp.NewTool("calculate",
	mcp.WithDescription("进行基础的数学运算"),
	mcp.WithString("operation",
		mcp.Required(),
		mcp.Description("The arithmetic operation to perform"),
		mcp.Enum("add", "subtract", "multiply", "divide"),
	),
	mcp.WithNumber("x",
		mcp.Required(),
		mcp.Description("First number"),
	),
	mcp.WithNumber("y",
		mcp.Required(),
		mcp.Description("Second number"),
	),
)
// 2. 实现工具的具体处理逻辑，类比大模型function_calling中的func部分
mcpServer.AddTool(calculatorTool, func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	op := request.Params.Arguments["operation"].(string)
	x := request.Params.Arguments["x"].(float64)
	y := request.Params.Arguments["y"].(float64)

	var result float64
	switch op {
	case "add":
		result = x + y
	case "subtract":
		result = x - y
	case "multiply":
		result = x * y
	case "divide":
		if y == 0 {
			return nil, errors.New("Division by zero is not allowed")
		}
		result = x / y
	}

	return mcp.FormatNumberResult(result), nil
})

// 给mcpServer添加提示词模版
mcpServer.AddPrompt(mcp.NewPrompt("打招呼",
	mcp.WithPromptDescription("A friendly greeting prompt"),
	mcp.WithArgument("name",
		mcp.ArgumentDescription("Name of the person to greet"),
	),
), func(ctx context.Context, request mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
	name := request.Params.Arguments["name"]
	if name == "" {
		name = "friend"
	}

	return mcp.NewGetPromptResult(
		"A friendly greeting",
		[]mcp.PromptMessage{
			mcp.NewPromptMessage(
				mcp.RoleAssistant,
				mcp.NewTextContent(fmt.Sprintf("Hello, %s! How can I help you today?", name)),
			),
		},
	), nil
})

package main

import (
	"context"
	"errors"
	"fmt"
	"github.com/mark3labs/mcp-go/mcp"
	"github.com/mark3labs/mcp-go/server"
	"io"
	"net"
	"net/http"
)

func main() {
	// Create MCP server
	s := server.NewMCPServer(
		"ip-mcp",
		"1.0.0",
	)

	// Add tool
	tool := mcp.NewTool("ip_query",
		mcp.WithDescription("query geo location of an IP address"),
		mcp.WithString("ip",
			mcp.Required(),
			mcp.Description("IP address to query"),
		),
	)

	// Add tool handler
	s.AddTool(tool, ipQueryHandler)

	// Start the stdio server
	if err := server.ServeStdio(s); err != nil {
		fmt.Printf("Server error: %v\n", err)
	}
}

func ipQueryHandler(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	ip, ok := request.Params.Arguments["ip"].(string)
	if !ok {
		return nil, errors.New("ip must be a string")
	}

	parsedIP := net.ParseIP(ip)
	if parsedIP == nil {
		return nil, errors.New("invalid IP address")
	}

	resp, err := http.Get("https://ip.rpcx.io/api/ip?ip=" + ip)
	if err != nil {
		return nil, fmt.Errorf("Error fetching IP information: %v", err)
	}
	defer resp.Body.Close()

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("Error reading response body: %v", err)
	}
	fmt.Printf("call ip: %s  Response body: %s\n", ip, string(data))
	return mcp.NewToolResultText(string(data)), nil
}

# 执行命令编译mcp server
go build -o mcp-ip main.go