Tetrad MCP server

Tetrad

Quadruple Consensus MCP Server for Claude Code

Tetrad is a high-performance MCP (Model Context Protocol) server written in Rust that orchestrates three AI-powered CLI code evaluation tools (Codex, Gemini CLI, Qwen) to validate all code produced by Claude Code.

The system implements a quadruple consensus protocol where no code or plan is accepted without approval from four intelligences: the three external evaluators + Claude Code itself.

Features

• Quadruple Consensus: 4 AI models must agree to approve code
• ReasoningBank: Continuous learning system with RETRIEVE→JUDGE→DISTILL→CONSOLIDATE cycle
• High Performance: Written in Rust with parallel execution via Tokio
• MCP Server: JSON-RPC 2.0 server over stdio for Claude Code integration
• Full CLI: Intuitive commands (init, serve, status, doctor, config, etc.)
• LRU Cache: Result caching with configurable TTL
• Hook System: Pre/post evaluation callbacks for customization
• Extensible: Plugin system for custom executors
• Cross-session: SQLite persistence for patterns and history

Quick Start

1. Install Tetrad

# Via npm (recommended - works seamlessly with Claude Code)
npm install -g @samoradc/tetrad

# Or via cargo (requires additional setup)
cargo install tetrad
sudo cp ~/.cargo/bin/tetrad /usr/local/bin/

1.1 Initialize in Your Project (Optional)

npx @samoradc/tetrad init

This will:

• Create tetrad.toml configuration file
• Create .tetrad/ directory for the database
• Add .tetrad/ to your .gitignore

2. Install and Configure External CLI Tools

Tetrad requires at least one of the following AI CLI tools. Good news: you don't need separate API keys if you have existing subscriptions!

Codex CLI (OpenAI)

npm install -g @openai/codex

Authentication options:

# Option 1: Login with your ChatGPT subscription (recommended)
codex login
# Opens browser for OAuth - follow the prompts

# Option 2: Use API key
export OPENAI_API_KEY="your-openai-key"

Note: For headless/remote servers, use codex login --device-auth and follow the device code flow.

📖 Codex CLI Authentication Docs

Gemini CLI (Google)

npm install -g @google/gemini-cli

Authentication options:

# Option 1: Login with Google account (recommended)
gemini auth login
# Opens browser for OAuth - follow the prompts

# Option 2: Use API key from Google AI Studio
export GEMINI_API_KEY="your-gemini-key"

Free Tier: With a personal Google account, you get access to Gemini 2.5 Pro with 1M token context window at no cost!

📖 Gemini CLI Authentication Docs

Qwen CLI (Alibaba)

Shortened. The full README is on GitHub.