Tetrad

io.github.SamoraDCPublished by GitHub account SamoraDCv0.1.12Updated Nov 10, 2026

Quadruple consensus MCP server for code validation using Codex, Gemini, and Qwen

VerifiedSTDIODesktop onlyDeveloper ToolsAI & ML

Overview

AI-generated overview

MCP server that sends code, plans and tests written by an AI assistant to Codex, Gemini and Qwen CLIs and returns a consensus verdict.

What you can do
  • Review plans, code and tests before they are saved or finalized
  • Confirm agreement with received feedback and run a final pre-commit check
  • Check the health and availability of the configured evaluator CLIs
  • Aggregate per-model votes into a pass or block decision with scores and suggestions
  • Store and reuse learned code patterns in a local SQLite ReasoningBank, with history, export and import commands
When to use it
Useful when you want a second, third and fourth opinion on AI-generated code before it is committed, especially for critical or security-sensitive changes. It fits teams already using Claude Code who want an automated review gate rather than manual cross-checking.
Requirements
Runs locally over stdio via the npm package, so Node.js is needed. At least one of the Codex, Gemini or Qwen CLI tools must be installed and authenticated; API keys such as OPENAI_API_KEY, GEMINI_API_KEY or DASHSCOPE_API_KEY are optional if you log in with an existing subscription or account. Network access is required for the evaluator CLIs.
Before you install
Code, plans and tests you submit are sent to third-party AI providers (OpenAI, Google, Alibaba) through their CLIs, so avoid confidential code unless that is acceptable. Credentials such as OPENAI_API_KEY, GEMINI_API_KEY or DASHSCOPE_API_KEY may be stored in project or user configuration files. It writes a config file, a .tetrad directory with a SQLite database, and edits .gitignore during initialization.

Installation

In SourceWeft

  1. Open Tetrad in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

Tetrad

[CI] [MCP Registry] [npm] [Crates.io] [Rust] [License: MIT]

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

bash
# Via npm (recommended - works seamlessly with Claude Code)npm install -g @samoradc/tetrad
# Or via cargo (requires additional setup)cargo install tetradsudo cp ~/.cargo/bin/tetrad /usr/local/bin/

1.1 Initialize in Your Project (Optional)

bash
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)
bash
npm install -g @openai/codex

Authentication options:

MethodRequirementsAPI Key Needed?
ChatGPT LoginChatGPT Plus, Pro, Business, Edu, or Enterprise subscriptionNo
API KeyOpenAI API account with creditsYes
bash
# Option 1: Login with your ChatGPT subscription (recommended)codex login# Opens browser for OAuth - follow the prompts
# Option 2: Use API keyexport 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)
bash
npm install -g @google/gemini-cli

Authentication options:

MethodRequirementsAPI Key Needed?Free Tier
Google LoginPersonal Google accountNo60 req/min, 1,000 req/day
API KeyGoogle AI Studio accountYesSame limits
bash
# 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 Studioexport 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)
bash
npm install -g qwen-code

Authentication options:

MethodRequirementsAPI Key Needed?Free Tier
DashScope APIAlibaba Cloud accountYes2,000 req/day
Coding PlanQwen Coding subscriptionYes (different format)Included
bash
# Get your API key from DashScope consoleexport DASHSCOPE_API_KEY="your-dashscope-key"
# For international users (outside China)export OPENAI_BASE_URL="https://dashscope-intl.aliyuncs.com/compatible-mode/v1"

Regional Endpoints:

  • Singapore: dashscope-intl.aliyuncs.com
  • Virginia: dashscope-us.aliyuncs.com
  • Beijing: dashscope.aliyuncs.com

📖 Qwen API Docs

3. Verify Installation

bash
# Check Tetrad versiontetrad version
# Check CLI availabilitytetrad status
# Diagnose any issuestetrad doctor

4. Add to Claude Code CLI

bash
# Add Tetrad as MCP server (all projects)claude mcp add --scope user tetrad -- npx @samoradc/tetrad serve
# Verify it's configuredclaude mcp list
Alternative installation methods
bash
# Current project onlyclaude mcp add tetrad -- npx @samoradc/tetrad serve
# If installed via cargoclaude mcp add --scope user tetrad -- tetrad serve

Note: Tetrad is published on the MCP Registry for discoverability and documentation.

5. Alternative: Manual Configuration

Create or edit .mcp.json in your project root:

json
{  "mcpServers": {    "tetrad": {      "type": "stdio",      "command": "npx",      "args": ["@samoradc/tetrad", "serve"],      "env": {        "OPENAI_API_KEY": "${OPENAI_API_KEY}",        "GOOGLE_API_KEY": "${GOOGLE_API_KEY}",        "DASHSCOPE_API_KEY": "${DASHSCOPE_API_KEY}"      }    }  }}

Or for global user configuration in ~/.claude.json (mcpServers section):

json
{  "mcpServers": {    "tetrad": {      "type": "stdio",      "command": "npx",      "args": ["@samoradc/tetrad", "serve"]    }  }}

How It Works

When you ask Claude Code to write code, Tetrad automatically validates it:

You: "Create a function in Rust that calculates the average of a vector"
Claude Code:1. Writes the code2. Calls tetrad_review_code automatically3. Tetrad sends to Codex, Gemini and Qwen for evaluation4. Returns consolidated consensus from all 3 evaluators
Tetrad Response:┌─────────────────────────────────────────────┐│ DECISION: PASS ✓                            ││ Score: 92/100                               ││ Consensus: Yes (3/3 approved)               ││                                             ││ Votes:                                      ││   • Codex:  Pass (95)                       ││   • Gemini: Pass (90)                       ││   • Qwen:   Pass (92)                       ││                                             ││ Suggestions:                                ││   - Consider handling empty vector case     │└─────────────────────────────────────────────┘
Claude Code: Saves the approved code

When Issues Are Found:

Tetrad Response:┌─────────────────────────────────────────────┐│ DECISION: BLOCK ✗                           ││ Score: 26/100                               ││ Consensus: Yes (3/3 rejected)               ││                                             ││ Votes:                                      ││   • Codex:  Fail (30) - division by zero    ││   • Gemini: Fail (25) - no error handling   ││   • Qwen:   Fail (25) - unsafe operation    ││                                             ││ Issues:                                     ││   - Division by zero not handled            ││   - Missing input validation                ││   - No Result/Option return type            │└─────────────────────────────────────────────┘
Claude Code: Fixes the code and resubmits

CLI Commands

tetrad - Quadruple Consensus CLI for Claude Code
COMMANDS:    init              Initialize configuration in current directory    serve             Start the MCP server (used by Claude Code)    status            Show CLI status (codex, gemini, qwen)    config            Configure options interactively    doctor            Diagnose configuration issues    version           Show version    evaluate          Evaluate code manually (without MCP)    history           Show evaluation history from ReasoningBank    export            Export patterns from ReasoningBank    import            Import patterns into ReasoningBank
OPTIONS:    -c, --config <FILE>    Configuration file (default: tetrad.toml)    -v, --verbose          Verbose mode    -q, --quiet            Quiet mode    -h, --help             Show help

MCP Tools

When running as MCP server, Tetrad exposes 6 tools:

ToolDescription
tetrad_review_planReview implementation plans before coding
tetrad_review_codeReview code before saving
tetrad_review_testsReview tests before finalizing
tetrad_confirmConfirm agreement with received feedback
tetrad_final_checkFinal verification before commit
tetrad_statusCheck health of evaluators

Workflow Example

1. Claude Code generates plan → tetrad_review_plan → Feedback2. Claude Code implements   → tetrad_review_code → Feedback3. Claude Code adjusts      → tetrad_confirm     → Confirmation4. Claude Code finalizes    → tetrad_final_check → Certificate

Architecture

Claude Code → MCP Protocol (stdio) → Tetrad Server (Rust)                                          │                    ┌─────────────────────┼─────────────────────┐                    ▼                     ▼                     ▼              Codex CLI            Gemini CLI              Qwen CLI              (syntax)            (architecture)           (logic)                    │                     │                     │                    └─────────────────────┼─────────────────────┘                                          ▼                                  Consensus Engine                                          │                            ┌─────────────┴─────────────┐                            ▼                           ▼                      LRU Cache                  ReasoningBank                      (results)                    (SQLite)                                    RETRIEVE→JUDGE→DISTILL→CONSOLIDATE

Executor Specializations

ExecutorCLISpecialization
Codexcodex exec --jsonSyntax and code conventions
Geminigemini -o jsonArchitecture and design
QwenqwenLogic bugs and correctness

Consensus Rules

RuleRequirementUse Case
GoldenUnanimity (3/3)Critical code, security
Strong3/3 or 2/3 with high confidenceDefault
WeakSimple majority (2/3)Rapid prototyping

ReasoningBank

The ReasoningBank is a continuous learning system that stores and consolidates code patterns:

Learning Cycle

RETRIEVE → JUDGE → DISTILL → CONSOLIDATE    │         │        │           │    │         │        │           └─ Merge similar patterns    │         │        └─ Extract new patterns    │         └─ Evaluate code with context    └─ Search for relevant patterns

Pattern Types

  • AntiPattern: Patterns to avoid (bugs, vulnerabilities, code smells)
  • GoodPattern: Patterns to follow (best practices, idiomatic patterns)
  • Ambiguous: Patterns with uncertain classification (needs more data)

ReasoningBank Commands

bash
# View evaluation historytetrad history --limit 50
# Export patterns to sharetetrad export -o team-patterns.json
# Import patterns from another ReasoningBanktetrad import team-patterns.json

Configuration

The tetrad.toml file is created automatically with tetrad init:

toml
[general]log_level = "info"timeout_secs = 60
[executors.codex]enabled = truecommand = "codex"args = ["exec", "--json"]timeout_secs = 30
[executors.gemini]enabled = truecommand = "gemini"args = ["-o", "json"]timeout_secs = 30
[executors.qwen]enabled = truecommand = "qwen"args = []timeout_secs = 30
[consensus]default_rule = "strong"min_score = 70max_loops = 3
[reasoning]enabled = truedb_path = ".tetrad/tetrad.db"max_patterns_per_query = 10consolidation_interval = 100
[cache]enabled = truecapacity = 1000ttl_secs = 300

Interactive Configuration

Use tetrad config for interactive configuration:

🔧 Tetrad Interactive Configuration
What would you like to configure?❯ General Settings  Executors (Codex, Gemini, Qwen)  Consensus  ReasoningBank  Save and Exit  Exit without Saving

LRU Cache

The system includes an LRU cache to avoid unnecessary re-evaluations:

  • Capacity: Configurable (default: 1000 entries)
  • TTL: Configurable time-to-live (default: 5 minutes)
  • Key: Hash of code + language + evaluation type
  • Invalidation: Automatic by TTL or manual

Hook System

Hooks allow customizing behavior at specific points:

HookWhenUse
pre_evaluateBefore evaluationModify request, skip evaluation
post_evaluateAfter evaluationLogging, metrics, notifications
on_consensusWhen consensus reachedAutomatic actions on approval
on_blockWhen code blockedAlerts, automatic rollback

Built-in Hooks

  • LoggingHook: Records all evaluations
  • MetricsHook: Collects usage statistics

Project Structure

tetrad/├── Cargo.toml              # Crate manifest├── CLAUDE.md               # Documentation for Claude Code├── README.md               # This file├── Tetrad.md               # Complete specification├── src/│   ├── main.rs             # Entry point (CLI)│   ├── lib.rs              # Exportable library│   ├── cli/│   │   ├── mod.rs          # CLI definition with clap│   │   ├── commands.rs     # Command implementations│   │   └── interactive.rs  # Interactive configuration (dialoguer)│   ├── executors/│   │   ├── mod.rs│   │   ├── base.rs         # CliExecutor trait│   │   ├── codex.rs        # Codex executor│   │   ├── gemini.rs       # Gemini executor│   │   └── qwen.rs         # Qwen executor│   ├── types/│   │   ├── mod.rs│   │   ├── config.rs       # TOML configuration│   │   ├── errors.rs       # TetradError/TetradResult│   │   ├── requests.rs     # EvaluationRequest│   │   └── responses.rs    # EvaluationResult, ModelVote│   ├── consensus/│   │   ├── mod.rs          # Exports│   │   ├── engine.rs       # ConsensusEngine│   │   ├── aggregator.rs   # Vote aggregation│   │   └── rules.rs        # Voting rules│   ├── reasoning/│   │   ├── mod.rs          # Exports│   │   ├── bank.rs         # ReasoningBank│   │   ├── patterns.rs     # Pattern types│   │   ├── sqlite.rs       # SQLite storage│   │   └── export.rs       # Import/Export│   ├── mcp/│   │   ├── mod.rs          # Exports│   │   ├── server.rs       # MCP server│   │   ├── protocol.rs     # JSON-RPC types│   │   ├── tools.rs        # Tool handlers│   │   └── transport.rs    # Stdio transport│   ├── cache/│   │   ├── mod.rs          # Exports│   │   └── lru.rs          # LRU cache│   └── hooks/│       ├── mod.rs          # Hook trait and HookSystem│       └── builtin.rs      # Default hooks└── tests/    ├── cli_integration.rs    ├── consensus_integration.rs    ├── mcp_integration.rs    └── reasoning_integration.rs

Development

bash
# Buildcargo buildcargo build --release
# Testscargo test                          # All testscargo test --lib                    # Unit tests onlycargo test --tests                  # Integration tests only
# Lintcargo clippy --all-targets --all-features -- -D warnings
# Formatcargo fmtcargo fmt --check
# Documentationcargo doc --open
# Run CLIcargo run -- statuscargo run -- doctorcargo run -- versioncargo run -- config

Troubleshooting

"CLI not found"

bash
# Check if CLIs are in PATHwhich codexwhich geminiwhich qwen
# Check configurationtetrad doctor

"stdin is not a terminal" (Codex)

Make sure your config uses exec --json:

toml
[executors.codex]args = ["exec", "--json"]

"Response does not contain valid JSON" (Gemini)

Make sure your config uses -o json:

toml
[executors.gemini]args = ["-o", "json"]

Check MCP status in Claude Code

Inside Claude Code, run:

/mcp

Prerequisites

To use Tetrad, you need at least one of the AI CLIs installed and authenticated:

CLIInstallationAuth Without API Key?Free Tier
Codex CLInpm i -g @openai/codex✅ ChatGPT Plus/Pro/BusinessVia subscription
Gemini CLInpm i -g @google/gemini-cli✅ Google account1,000 req/day
Qwen CLInpm i -g qwen-code❌ DashScope key required2,000 req/day

Check availability with:

bash
tetrad statustetrad doctor

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

  1. Fork the repository
  2. Create your feature branch (git checkout -b feature/amazing-feature)
  3. Commit your changes (git commit -m 'Add some amazing feature')
  4. Push to the branch (git push origin feature/amazing-feature)
  5. Open a Pull Request

License

MIT

Author

SamoraDC

Links:

Source: README.md at commit dc5874e

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v0.1.12LatestSep 16, 2026

Score

50% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts