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io.github.paiml/pmcp

High-quality Rust SDK for Model Context Protocol (MCP) with full TypeScript SDK compatibility

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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 reference guide with 27 chapters
🎓 pmcp-course - Hands-on course with quizzes and exercises
🤖 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 Course | AI Agents README

⚡ 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

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

Use the pmcp crate directly for maximum control:

Installation:

[dependencies]
pmcp = "2.0"
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 | pmcp-course | 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
Workflows: Multi-step orchestration with array indexing support
MCP Apps: Rich HTML UI widgets with live preview and browser DevTools
MCP Tasks: Shared client/server state with task lifecycle management
Tower Middleware: DNS rebinding protection, CORS, security headers
Typed Client Helpers: call_tool_typed, get_prompt_typed, and auto-paginating list_all_* with bounded safety cap
Performance: 16x faster than TypeScript, SIMD-accelerated parsing
Quality: Zero unwrap(), comprehensive error handling

Latest Version: pmcp = "2.6"

Documentation:

⚡ cargo-pmcp (CLI Toolkit)

Full-lifecycle development toolkit — from scaffolding to production deployment.

cargo install cargo-pmcp

cargo pmcp new my-workspace             # Scaffold a new workspace
cargo pmcp add server my-server         # Add a server with best-practice template
cargo pmcp dev --server my-server       # Dev server with hot-reload
cargo pmcp test --server my-server      # Auto-generated scenario tests
cargo pmcp loadtest run                 # Load test with latency percentiles
cargo pmcp pentest run                  # Security audit (32 checks, SARIF output)
cargo pmcp preview --open               # Browser-based widget preview
cargo pmcp deploy --target aws-lambda   # Deploy to AWS Lambda, GCR, or Cloudflare
cargo pmcp deploy logs --tail           # Stream production logs

Covers the full development lifecycle: scaffolding, dev mode, testing, load testing, security pentesting, MCP Apps preview, schema management, multi-target deployment, secrets, and OAuth setup.

Full command reference: cargo-pmcp Guide

📚 pmcp-book (Reference Guide)

27-chapter comprehensive reference 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

🎓 pmcp-course (Hands-On Learning)

Interactive course with quizzes, exercises, and real-world projects for mastering MCP development.

🎓 Start the Course

Course Structure:

Part I: Foundations - MCP concepts, first server, typed tools
Part II: Core Concepts - Tools, resources, prompts, validation
Part III: Deployment - AWS Lambda, Cloudflare Workers, Google Cloud Run
Part IV: Testing - Local testing, CI/CD, regression testing
Part V: Security - OAuth 2.0, identity providers, multi-tenant
Part VI: AI-Assisted Dev - Claude Code, feedback loops, collaboration
Part VII: Observability - Middleware, logging, metrics
Part VIII: Advanced - Server composition, MCP Apps (experimental)

Features:

Interactive quizzes after each chapter
Hands-on exercises with solutions
Real-world project examples
Best practices from production servers

Local development:

cd pmcp-course && mdbook serve    # Serve at http://localhost:3000

🤖 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 Course | ai-agents/

🎨 MCP Apps (Rich UI Widgets)

Build rich HTML UI widgets served from MCP servers — works with ChatGPT, Claude, and other MCP clients.

What it does:

Preview: Live widget preview with dual proxy/WASM bridge modes
Author: File-based widgets in widgets/ directory with hot-reload
Scaffold: cargo pmcp app new generates a complete MCP Apps project
Publish: ChatGPT-compatible manifest and standalone demo landing pages
Test: 20 E2E browser tests via chromiumoxide CDP

Quick start:

# Scaffold a new MCP Apps project
cargo pmcp app new my-widget-app
cd my-widget-app

# Run the server
cargo run

# Preview in browser (separate terminal)
cargo pmcp preview --url http://localhost:3000 --open

# Generate deployment artifacts
cargo pmcp app build --url https://my-server.example.com

Examples:

Chess App — Interactive chess board with move validation
Map App — Leaflet.js geospatial city explorer
Data Viz App — Chart.js dashboard with SQL queries

Learn more: Widget Runtime | Preview Server | E2E Tests

Latest Release: v2.0.0

PMCP v2.0 — aligned with the MCP TypeScript SDK v2.0 release (2026-03-22):

Protocol v2025-11-25: Full alignment with the latest MCP specification, backward compatible with 2024-11-05
MCP Apps: Rich interactive HTML UI widgets served from MCP servers — works with ChatGPT, Claude Desktop, and other MCP clients. Live preview with browser-style DevTools (resizable panel, network/events/protocol/bridge tabs)
MCP Tasks: Experimental shared client/server state with DynamoDB-backed task lifecycle management and task variables
Conformance Test Suite: 19-scenario conformance engine across 5 domains with cargo pmcp test conformance and mcp-tester conformance CLI integration
Tower Middleware: DNS rebinding protection, CORS with origin-locked headers, configurable security headers — production-ready HTTP stack
PMCP Server: MCP server exposing SDK developer tools (test, scaffold, schema export) via Streamable HTTP, deployed on AWS Lambda
Uniform Constructor DX: Default impls, builders, and constructors for all protocol types — dramatically improved ergonomics
60+ Examples: Comprehensive coverage of all SDK features

Full changelog: CHANGELOG.md

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 Documentation Portal - Landing page for all documentation
pmcp-book - Comprehensive reference guide (27 chapters)
pmcp-course - Hands-on course with quizzes and exercises
API Reference - Complete API documentation
cargo-pmcp Guide - CLI toolkit documentation

📚 Additional Resources

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

🎯 Quick Links

Examples

The SDK includes 60+ comprehensive examples covering all features:

# Basic examples
cargo run --example c01_client_initialize   # Client setup
cargo run --example s01_basic_server        # Basic server
cargo run --example c02_client_tools        # Tool usage

# Type-safe tools (v1.6.0+)
cargo run --example s16_typed_tools --features schema-generation
cargo run --example s17_advanced_typed_tools --features schema-generation

# Advanced features
cargo run --example s28_authentication      # OAuth/Bearer
cargo run --example t01_websocket_transport # WebSocket
cargo run --example m01_basic_middleware    # Middleware chain

# Testing (mcp-tester is a standalone Cargo project in examples/26-server-tester)
cargo install mcp-tester && mcp-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.

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

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 t08_simd_parsing_performance  # SIMD-specific

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 1.83.0 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:

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

See: CONTRIBUTING.md

Compatibility

Feature	TypeScript SDK v2.0	PMCP v2.0 (Rust)
Protocol Version	2025-11-25	2025-11-25 (+ 2024-11-05 compat)
Transports	stdio, SSE, WebSocket	stdio, SSE, WebSocket, WASM
Authentication	OAuth 2.0, Bearer	OAuth 2.0, Bearer, OIDC
Tools	✓	✓ (Type-safe + outputSchema)
Prompts	✓	✓ (Workflows)
Resources	✓	✓ (Subscriptions)
Sampling	✓	✓
MCP Apps	✓	✓ (Preview + DevTools)
Tower Middleware	N/A	✓ (DNS rebinding, CORS, security headers)
Performance	1x	16x faster
Memory	Baseline	50x lower

License

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

Acknowledgments

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