MCP Server with Go

1.txt

$export ANTHROPIC_API_KEY='your-api-key' 
$mcphost --config ./mcp-server.json

2025/02/18 23:50:07 INFO Model loaded provider=anthropic model=claude-3-5-sonnet-latest
2025/02/18 23:50:07 INFO Initializing server... name=mcp-calculator-with-docker
2025/02/18 23:50:09 INFO Server connected name=mcp-calculator-with-docker
2025/02/18 23:50:09 INFO Tools loaded server=mcp-calculator-with-docker count=1
┃ Enter your prompt (Type /help for commands, Ctrl+C to quit)            
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Dockerfile

FROM golang:1.23.6-alpine3.21 AS builder
WORKDIR /app
COPY . .
RUN go mod tidy
RUN go build -o calculator

FROM alpine:3.21
WORKDIR /app
RUN apk add --no-cache ca-certificates
COPY --from=builder /app/calculator .
ENTRYPOINT ["./calculator"]

main.go

package main

import (
	"context"
	"fmt"

	"github.com/mark3labs/mcp-go/mcp"
	"github.com/mark3labs/mcp-go/server"
)

func main() {
	// Create a new MCP server
	s := server.NewMCPServer(
		"demo",
		"1.0.0",
		server.WithResourceCapabilities(true, true),
		server.WithLogging(),
	)

	// Add a calculator tool
	calculatorTool := mcp.NewTool("calculate",
		mcp.WithDescription("Perform basic arithmetic operations"),
		mcp.WithString("operation",
			mcp.Required(),
			mcp.Description("The operation to perform (add, subtract, multiply, divide)"),
			mcp.Enum("add", "subtract", "multiply", "divide"),
		),
		mcp.WithNumber("x",
			mcp.Required(),
			mcp.Description("First number"),
		),
		mcp.WithNumber("y",
			mcp.Required(),
			mcp.Description("Second number"),
		),
	)

	// Add the calculator handler
	s.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 mcp.NewToolResultError("Cannot divide by zero"), nil
			}
			result = x / y
		}

		return mcp.NewToolResultText(fmt.Sprintf("%.2f", result)), nil
	})

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

mcp-server.json

{
    "mcpServers": {
      "mcp-calculator-with-docker" :{
        "command": "docker",
        "args": [
          "run",
          "--rm",
          "-i",
          "calculator"
        ]
      }
    }
  }