rust-mcp-playground

Rust MCP Playground

A complete working implementation of the Model Context Protocol (MCP) in Rust, featuring both client and server components with full tool integration.

🚀 Quick Start

Run the interactive calculator chat client:

cd projects/client
cargo run

This will:

• Automatically start the calculator server
• Connect to Claude via Anthropic API
• Provide a chat interface for mathematical operations

Example usage:

You: add 15 to 27
🤖 Assistant: 15 + 27 = 42

You: what's the square root of 144?
🤖 Assistant: √144 = 12

📁 Project Structure

rust-mcp-playground/
├── projects/                     # 🎯 Main implementations
│   ├── client/                   # Chat client with Anthropic integration
│   │   ├── .env                  # ANTHROPIC_API_KEY configuration
│   │   └── src/main.rs           # Full MCP client implementation
│   └── servers/calculator/       # Calculator MCP server
│       └── src/main.rs           # 6 mathematical tools
├── references/                   # 📚 Official examples
│   └── rust-mcp-sdk-examples/    # Complete SDK reference implementations
└── CLAUDE.md                     # Development guidance

✨ Features

🧮 Calculator Server

• 6 Mathematical Tools: add, subtract, multiply, divide, square, sqrt
• Error Handling: Division by zero, negative square roots, invalid inputs
• Input Validation: NaN and infinity checks
• MCP Protocol: Latest rmcp 0.2.1 with #[tool_router] macros
• Comprehensive Testing: Unit tests for all operations

💬 Chat Client

• Natural Language Interface: Ask questions in plain English
• Tool Discovery: Automatically finds and uses server capabilities
• Anthropic Integration: Uses Claude for intelligent responses
• STDIO Transport: Manages server process lifecycle
• Environment Configuration: API key from .env file

🛠️ Technical Implementation

Built with the official Rust MCP SDK:

• rmcp 0.2.1 - Latest MCP implementation
• Protocol Version: 2024-11-05 (current MCP standard)
• Transport: STDIO (standard for MCP integrations)
• Tool Registration: Declarative macros for clean implementation

Architecture:

// Server tool registration
#[tool_router]
impl Calculator {
    #[tool(description = "Add two numbers together")]
    fn add(&self, Parameters(AddRequest { a, b }): Parameters<AddRequest>) 
        -> Result<CallToolResult, McpError> { /* ... */ }
}

// Client spawns server and discovers tools automatically
let transport = TokioChildProcess::new(command)?;
let client = ().serve(transport).await?;
let tools = client.list_all_tools().await?; // Discovers all 6 calculator tools

📋 Prerequisites

1. Rust (edition 2024)

2. Anthropic API Key - Add to projects/client/.env:

   ANTHROPIC_API_KEY=your_key_here
   

🧪 Development

Run tests:

cd projects/servers/calculator
cargo test

Build components independently:

# Server only
cd projects/servers/calculator
cargo build

# Client only  
cd projects/client
cargo build

Debug server separately:

cd projects/servers/calculator
cargo run  # Waits for STDIO input

📖 Learning Resources

• Official MCP SDK: https://github.com/modelcontextprotocol/rust-sdk
• MCP Specification: https://modelcontextprotocol.io/
• Reference Examples: See references/rust-mcp-sdk-examples/ for comprehensive examples

🎯 What Makes This Special

This isn't just example code - it's a fully functional MCP system that demonstrates:

✅ Real-world MCP integration with working tool discovery and execution
✅ Production-ready patterns with proper error handling and validation
✅ Modern Rust MCP development using the latest SDK features
✅ Complete client-server architecture with automatic process management
✅ Natural language interface powered by Claude's intelligence

Perfect for learning MCP concepts, building new MCP tools, or integrating MCP into existing applications!