PMCP - Pragmatic Model Context Protocol

Production-grade Rust implementation of the Model Context Protocol (MCP) - 16x faster than TypeScript, built with Toyota Way quality principles

Overview

PMCP is a complete MCP ecosystem for Rust, providing everything you need to build, test, and deploy production-grade MCP servers:

• 🦀 pmcp SDK - High-performance Rust crate with full MCP protocol support
• ⚡ cargo-pmcp - CLI toolkit for scaffolding, testing, and development
• 📚 pmcp-book - Comprehensive guide with 27 chapters
• 🤖 AI Agents - Kiro and Claude Code configurations for AI-assisted development

Why PMCP?

• Performance: 16x faster than TypeScript SDK, 50x lower memory
• Safety: Rust's type system + zero unwrap() in production code
• Quality: Toyota Way principles - zero technical debt tolerance
• Complete: SDK, tooling, documentation, and AI assistance in one ecosystem

Quick Start

Choose your path based on experience and preference:

🚀 Path 1: AI-Assisted (Fastest - Recommended for Rapid Prototyping)

Build production-ready MCP servers with AI assistance in minutes:

Prerequisites:

# Install Rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
rustup update

# Install cargo-pmcp
cargo install cargo-pmcp

Install Claude Code AI Agent:

# Install the mcp-developer subagent (user-level - works across all projects)
curl -fsSL https://raw.githubusercontent.com/paiml/rust-mcp-sdk/main/ai-agents/claude-code/mcp-developer.md \
  -o ~/.claude/agents/mcp-developer.md

# Restart Claude Code

Build your server:

You: "Create a weather forecast MCP server with tools for getting current conditions and 5-day forecasts"

Claude Code: [Invokes mcp-developer subagent]

I'll create a production-ready weather MCP server using cargo-pmcp.

$ cargo pmcp new weather-mcp-workspace
$ cd weather-mcp-workspace
$ cargo pmcp add server weather --template minimal

[Implements type-safe tools with validation]
[Adds comprehensive tests and observability]
[Validates quality gates]

✅ Production-ready server complete with 85% test coverage!

What you get: Production-ready code following Toyota Way principles, with comprehensive tests, structured logging, metrics collection, and zero clippy warnings.

Learn more: AI-Assisted Development Guide | AI Agents README

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⚡ Path 2: cargo-pmcp Toolkit (Recommended for Manual Development)

Scaffold and build servers using the cargo-pmcp CLI:

Installation:

# Install Rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
rustup update

# Install cargo-pmcp
cargo install cargo-pmcp

Create a server:

# Create workspace
cargo pmcp new my-mcp-workspace
cd my-mcp-workspace

# Add a server using a template
cargo pmcp add server myserver --template minimal

# Start development server with hot-reload
cargo pmcp dev --server myserver

# Generate and run tests
cargo pmcp test --server myserver --generate-scenarios
cargo pmcp test --server myserver

# Build for production
cargo build --release

Available templates:

• minimal - Empty structure for custom servers
• calculator - Arithmetic operations (learning)
• complete_calculator - Full-featured reference implementation
• sqlite_explorer - Database browser pattern

Learn more: cargo-pmcp Guide

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🦀 Path 3: pmcp SDK Directly (For Fine-Grained Control)

Use the pmcp crate directly for maximum control:

Installation:

[dependencies]
pmcp = "1.8"
tokio = { version = "1", features = ["full"] }
serde = { version = "1", features = ["derive"] }
schemars = "0.8"  # For type-safe tools

Type-safe server example:

use pmcp::{ServerBuilder, TypedTool, RequestHandlerExtra, Error};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};

#[derive(Debug, Deserialize, Serialize, JsonSchema)]
#[schemars(deny_unknown_fields)]
struct WeatherArgs {
    #[schemars(description = "City name")]
    city: String,

    #[schemars(description = "Number of days (1-5)")]
    days: Option<u8>,
}

#[derive(Debug, Serialize, JsonSchema)]
struct WeatherOutput {
    temperature: f64,
    conditions: String,
}

async fn get_weather(args: WeatherArgs, _extra: RequestHandlerExtra) -> pmcp::Result<WeatherOutput> {
    // Validate
    if args.city.is_empty() {
        return Err(Error::validation("City cannot be empty"));
    }

    let days = args.days.unwrap_or(1);
    if !(1..=5).contains(&days) {
        return Err(Error::validation("Days must be 1-5"));
    }

    // Call weather API...
    Ok(WeatherOutput {
        temperature: 72.0,
        conditions: "Sunny".to_string(),
    })
}

#[tokio::main]
async fn main() -> pmcp::Result<()> {
    let server = ServerBuilder::new()
        .name("weather-server")
        .version("1.0.0")
        .tool("get-weather", TypedTool::new("get-weather", |args, extra| {
            Box::pin(get_weather(args, extra))
        }).with_description("Get weather forecast for a city"))
        .build()?;

    server.run_stdio().await?;
    Ok(())
}

Learn more: pmcp-book | API Documentation

---

PMCP Ecosystem Components

🦀 pmcp SDK (The Crate)

High-performance Rust implementation of the MCP protocol.

Key Features:

• Type-Safe Tools: Automatic JSON schema generation from Rust types
• Multiple Transports: stdio, HTTP/SSE, WebSocket, WASM
• OAuth Support: Full auth context pass-through (v1.8.0+)
• Workflows: Multi-step orchestration with array indexing support
• Performance: 16x faster than TypeScript, SIMD-accelerated parsing
• Quality: Zero unwrap(), comprehensive error handling

Latest Version: pmcp = "1.8.3"

Documentation:

• API Reference
• pmcp-book
• Examples

---

⚡ cargo-pmcp (CLI Toolkit)

Scaffolding and development toolkit for MCP servers.

What it does:

• Scaffold servers in seconds with proven patterns
• Hot-reload dev server for rapid iteration
• Generate test scenarios automatically
• Validate quality gates (fmt, clippy, tests)
• Deploy to production - AWS Lambda or Cloudflare Workers
• Manage deployments - logs, metrics, secrets, rollback

Commands:

cargo pmcp new <workspace>              # Create workspace
cargo pmcp add server <name>            # Add server
cargo pmcp dev --server <name>          # Start dev server
cargo pmcp test --server <name>         # Run tests
cargo pmcp deploy --target <target>     # Deploy to production
cargo pmcp deploy logs --tail           # Stream logs
cargo pmcp deploy destroy --clean       # Remove deployment

Why use it?

• Encodes best practices from 6 production servers
• Saves 30-60 minutes vs manual setup
• Ensures consistent structure across servers
• Integrated testing and quality validation

Learn more: cargo-pmcp Guide

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📚 pmcp-book (Comprehensive Guide)

27-chapter comprehensive guide to building MCP servers with pmcp.

📖 Read Online

Coverage:

• Getting Started: Installation, first server, quick start tutorial
• Core Concepts: Tools, resources, prompts, error handling
• Advanced Features: Auth, transports, middleware, progress tracking
• Real-World: Production servers, testing, deployment, performance
• Examples & Patterns: Complete examples and design patterns
• TypeScript Migration: Complete compatibility guide
• Advanced Topics: Custom transports, AI-assisted development

Local development:

make book-serve    # Serve at http://localhost:3000
make book-open     # Build and open in browser

---

🤖 ai-agents (AI-Assisted Development)

AI agent configurations that teach Kiro and Claude Code how to build MCP servers.

Supported AI Assistants:

Kiro (Steering Files) - 10,876 lines of persistent MCP expertise

• Always-active knowledge in every conversation
• Comprehensive testing and observability guidance
• Installation Guide

Claude Code (Subagent) - ~750 lines of focused MCP knowledge

• On-demand invocation for MCP tasks
• Quick scaffolding and implementation
• Installation Guide

What AI agents know:

• MCP protocol concepts and patterns
• cargo-pmcp workflow (never creates files manually)
• Type-safe tool implementation
• Testing strategies (unit, integration, property, fuzz)
• Production observability (logging, metrics)
• Toyota Way quality standards

Community implementations welcome:

• GitHub Copilot, Cursor, Cline, and others
• Contribution Guide

Learn more: AI-Assisted Development | ai-agents/

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Latest Release: v1.8.3

Highlights:

• 🔐 OAuth Auth Context: Full token pass-through from transport → middleware → tools
• 📋 Workflow Array Indexing: Access array elements in workflow templates
• 🛡️ Spec Compliance: Fixed ClientCapabilities schema for Cursor IDE compatibility
• 🔧 Type-Safe Tools: Production-ready typed tools with schema generation
• ⚡ Performance: SIMD-accelerated parsing (10.3x speedup)

Full changelog: CHANGELOG.md

Migration guides:

• v1.8.0 OAuth Migration
• v1.7.0 ClientCapabilities Fix

---

Core Features

🚀 Transport Layer

• stdio: Standard input/output for CLI integration
• HTTP/SSE: Streamable HTTP with Server-Sent Events
• WebSocket: Full-duplex with auto-reconnection
• WASM: Browser and Cloudflare Workers support

🛠️ Type-Safe Development

• Automatic Schema Generation: From Rust types using schemars
• Compile-Time Validation: Type-checked tool arguments
• Runtime Validation: Against generated JSON schemas
• Zero Unwraps: Explicit error handling throughout

🔐 Security & Auth

• OAuth 2.0: Full auth context pass-through
• OIDC Discovery: Automatic provider configuration
• Bearer Tokens: Standard authentication
• Path Validation: Secure file system access

🧪 Testing & Quality

• mcp-tester: Comprehensive server testing tool
• Scenario Generation: Auto-generate test cases
• Property Testing: Invariant validation
• Quality Gates: fmt, clippy, coverage enforcement

⚡ Performance

• 16x faster than TypeScript SDK
• 50x lower memory usage
• SIMD Parsing: 10.3x SSE speedup with AVX2/SSE4.2
• Connection Pooling: Smart load balancing

🏭 Toyota Way Quality

• Zero Technical Debt: TDG score 0.76
• Jidoka: Stop the line on defects
• Genchi Genbutsu: Go and see (evidence-based)
• Kaizen: Continuous improvement
• No Unwraps: Explicit error handling only

---

Documentation

📖 Primary Resources

• pmcp-book - Comprehensive guide (27 chapters)
• API Reference - Complete API documentation
• cargo-pmcp Guide - CLI toolkit documentation
• AI-Assisted Development - Building with AI

📚 Additional Resources

• Examples - 200+ working examples
• CHANGELOG - Version history
• Migration Guides - Upgrade instructions
• Contributing - How to contribute

🎯 Quick Links

• Quick Start Tutorial
• Your First Server
• Testing Guide
• Production Deployment

---

Examples

The SDK includes 60+ comprehensive examples covering all features:

# Basic examples
cargo run --example 01_client_initialize    # Client setup
cargo run --example 02_server_basic         # Basic server
cargo run --example 03_client_tools         # Tool usage

# Type-safe tools (v1.6.0+)
cargo run --example 32_typed_tools --features schema-generation
cargo run --example 33_advanced_typed_tools --features schema-generation

# Advanced features
cargo run --example 09_authentication       # OAuth/Bearer
cargo run --example 13_websocket_transport  # WebSocket
cargo run --example 15_middleware           # Middleware chain

# Testing
cargo run --example 26-server-tester -- test http://localhost:8080

# AI-assisted development
# See ai-agents/README.md for Kiro and Claude Code setup

See examples/README.md for complete list.

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MCP Server Tester

Comprehensive testing tool for validating MCP server implementations.

Features:

• Protocol compliance validation (JSON-RPC 2.0, MCP spec)
• Multi-transport support (HTTP, HTTPS, WebSocket, stdio)
• Tool discovery and testing
• CI/CD ready with JSON output

Installation:

cargo install mcp-server-tester

# Or download pre-built binaries from releases

Usage:

# Test a server
mcp-tester test http://localhost:8080

# Protocol compliance check
mcp-tester compliance http://localhost:8080 --strict

# Connection diagnostics
mcp-tester diagnose http://localhost:8080

Learn more: examples/26-server-tester/README.md

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Quality & Performance

Toyota Way Principles

PMCP is built following Toyota Production System principles:

• Jidoka (自働化): Automation with human touch

  • Quality gates stop builds on defects
  • Zero tolerance for unwrap() in production
  • Comprehensive error handling with context

• Genchi Genbutsu (現地現物): Go and see

  • Evidence-based decisions with metrics
  • PMAT quality analysis (TDG score 0.76)
  • Comprehensive testing (unit, property, fuzz)

• Kaizen (改善): Continuous improvement

  • Regular benchmarking and optimization
  • Performance regression prevention
  • Community-driven enhancements

Quality Metrics

• TDG Score: 0.76 (production-ready)
• Technical Debt: Minimal (436h across entire codebase)
• Complexity: All functions ≤25 complexity
• Coverage: 52% line coverage, 100% function coverage
• Linting: Zero clippy warnings in production code

Performance Benchmarks

Metric                  PMCP (Rust)     TypeScript SDK    Improvement
────────────────────────────────────────────────────────────────────
Overall Speed           16x             1x                16x faster
Memory Usage            <10 MB          ~500 MB           50x lower
SSE Parsing             336,921 ev/s    32,691 ev/s       10.3x faster
JSON-RPC Parsing        195,181 docs/s  N/A               SIMD-optimized
Round-trip Latency      <100 μs         ~1-2 ms           10-20x faster
Base64 Operations       252+ MB/s       N/A               Optimized

Run benchmarks:

make bench                           # General benchmarks
cargo run --example 32_simd_parsing  # SIMD-specific

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WebAssembly Support

Full WASM support for browser and edge deployment:

Targets:

• Cloudflare Workers (wasm32-unknown-unknown)
• WASI Runtimes (wasm32-wasi)
• Browser (wasm-bindgen)

Quick start:

# Build for Cloudflare Workers
cargo build --target wasm32-unknown-unknown --no-default-features --features wasm

# Deploy
make cloudflare-sdk-deploy

Learn more: WASM Guide | WASM Example

---

Development

Prerequisites

• Rust 1.82.0 or later
• Git

Setup

git clone https://github.com/paiml/rust-mcp-sdk
cd rust-mcp-sdk

# Install development tools
make setup

# Run quality checks
make quality-gate

Testing

make test-all           # All tests
make test-property      # Property tests
make coverage           # Coverage report
make mutants            # Mutation tests

Contributing

We welcome contributions! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Ensure quality gates pass (make quality-gate)
4. Commit with conventional commits
5. Push and open a Pull Request

See: CONTRIBUTING.md

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Compatibility

Feature	TypeScript SDK	PMCP (Rust)
Protocol Version	2024-10-07+	2024-10-07+
Transports	stdio, SSE, WebSocket	stdio, SSE, WebSocket, WASM
Authentication	OAuth 2.0, Bearer	OAuth 2.0, Bearer, OIDC
Tools	✓	✓ (Type-safe)
Prompts	✓	✓ (Workflows)
Resources	✓	✓ (Subscriptions)
Sampling	✓	✓
Performance	1x	16x faster
Memory	Baseline	50x lower

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Acknowledgments

• Model Context Protocol specification
• TypeScript SDK for reference implementation
• PAIML MCP Agent Toolkit for quality standards
• Community contributors and early adopters

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Links

• Documentation: https://paiml.github.io/rust-mcp-sdk/
• Crates.io: https://crates.io/crates/pmcp
• API Docs: https://docs.rs/pmcp
• Issues: https://github.com/paiml/rust-mcp-sdk/issues
• Discussions: https://github.com/paiml/rust-mcp-sdk/discussions

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Built with 🦀 Rust and ❤️ following Toyota Way principles