MCP Go Starter

A feature-complete Model Context Protocol (MCP) server template in Go using the official go-sdk. This starter demonstrates all major MCP features with clean, idiomatic Go code.

📚 Documentation

• Model Context Protocol
• Go SDK
• Building MCP Servers

✨ Features

MCP sampling (ask_llm) is deprecated as of protocol version 2026-07-28 (SEP-2577). This workshop keeps the example during the supported deprecation window; new production servers should call LLM provider APIs directly.

🚀 Quick Start

Prerequisites

• Go 1.26.8+
• (Optional) air for live reload
• (Optional) golangci-lint for linting

Air and goimports are pinned in tools/go.mod, including their transitive dependencies, and updated by Dependabot alongside the server modules. Install them with go -C tools install tool.

Installation

# Clone the repository
git clone https://github.com/SamMorrowDrums/mcp-go-starter.git
cd mcp-go-starter

# Download dependencies
go mod download

Running the Server

stdio transport (for local development):

go run ./cmd/stdio
# Or: make run-stdio

HTTP transport (for remote/web deployment):

go run ./cmd/http
# Or: make run-http
# Server runs on http://localhost:3000

The HTTP endpoint requires JSON requests and rejects cross-origin browser requests. Native MCP clients without an Origin header and same-origin browser clients remain supported.

Building Binaries

make build
# Creates bin/stdio and bin/http

🔧 VS Code Integration

This project includes VS Code configuration for seamless development:

1. Open the project in VS Code
2. The MCP configuration is in .vscode/mcp.json
3. Build with Ctrl+Shift+B (or Cmd+Shift+B on Mac)
4. Test the server using VS Code's MCP tools

Using DevContainers

1. Install the Dev Containers extension
2. Open command palette: "Dev Containers: Reopen in Container"
3. Everything is pre-configured and ready to use!

📁 Project Structure

.
├── cmd/
│   ├── stdio/
│   │   └── main.go        # stdio transport entrypoint
│   └── http/
│       └── main.go        # HTTP transport entrypoint
├── internal/
│   └── server/
│       ├── server.go      # Server orchestration
│       ├── tools.go       # Tool definitions (hello, get_weather, etc.)
│       ├── resources.go   # Resource and template definitions
│       └── prompts.go     # Prompt definitions
├── .vscode/
│   ├── mcp.json           # MCP server configuration
│   ├── tasks.json         # Build/run tasks
│   └── extensions.json
├── .devcontainer/
│   └── devcontainer.json
├── .air.toml              # Live reload configuration
├── .golangci.yml          # Linter configuration
├── go.mod
├── Makefile
└── README.md

🛠️ Development

# Development with live reload (recommended)
make dev
# Requires air: go install github.com/air-verse/air@latest

# Run without live reload
make run-stdio

# Run tests
make test

# Format code
make fmt

# Lint code
make lint

# Install all dev tools
make install-tools

# Clean build artifacts
make clean

Live Reload

Install air for automatic rebuilds:

go install github.com/air-verse/air@latest
make dev

Changes to any .go file will automatically rebuild and restart the server.

🔍 MCP Inspector

The MCP Inspector is an essential development tool for testing and debugging MCP servers.

Running Inspector

npx @modelcontextprotocol/inspector -- go run ./cmd/stdio/main.go

What Inspector Provides

• Tools Tab: List and invoke all registered tools with parameters
• Resources Tab: Browse and read resources and templates
• Prompts Tab: View and test prompt templates
• Logs Tab: See JSON-RPC messages between client and server
• Schema Validation: Verify tool input/output schemas

Debugging Tips

1. Start Inspector before connecting your IDE/client
2. Use the "Logs" tab to see exact request/response payloads
3. Test tool annotations (ToolAnnotations) are exposed correctly
4. Verify progress notifications appear for long_task
5. Check that sampling works with ask_llm

📖 Feature Examples

Tool with Annotations

mcp.AddTool(server, &mcp.Tool{
    Name:        "hello",
    Title:       "Say Hello",
    Description: "A friendly greeting tool",
    Annotations: &mcp.ToolAnnotations{
        ReadOnlyHint: ptr(true),
    },
}, helloHandler)

func helloHandler(ctx context.Context, req *mcp.CallToolRequest, input helloInput) (*mcp.CallToolResult, any, error) {
    return &mcp.CallToolResult{
        Content: []mcp.Content{
            &mcp.TextContent{Text: fmt.Sprintf("Hello, %s!", input.Name)},
        },
    }, nil, nil
}

Resource Template

server.AddResourceTemplate(&mcp.ResourceTemplate{
    Name:        "Personalized Greeting",
    URITemplate: "greeting://{name}",
    MIMEType:    "text/plain",
}, greetingHandler)

Tool with Progress Updates

func longTaskHandler(ctx context.Context, req *mcp.CallToolRequest, input longTaskInput) (*mcp.CallToolResult, any, error) {
    progressToken := req.Params.GetProgressToken()
    
    for i := 0; i < 5; i++ {
        req.Session.NotifyProgress(ctx, &mcp.ProgressNotificationParams{
            ProgressToken: progressToken,
            Progress:      float64(i) / 5.0,
            Total:         1.0,
        })
        time.Sleep(time.Second)
    }
    
    return &mcp.CallToolResult{
        Content: []mcp.Content{&mcp.TextContent{Text: "Done!"}},
    }, nil, nil
}

Tool with Sampling

result, err := req.Session.CreateMessage(ctx, &mcp.CreateMessageParams{
    Messages: []*mcp.SamplingMessage{
        {Role: "user", Content: &mcp.TextContent{Text: prompt}},
    },
    MaxTokens: 100,
})

🔐 Environment Variables

Copy .env.example to .env and configure:

cp .env.example .env

🤝 Contributing

Contributions welcome! Please ensure your changes maintain feature parity with other language starters.

📄 License

MIT License - see LICENSE for details.