Vibe Check

The definitive Vibe Coder's sanity check MCP server: Prevents cascading errors by calling a "Vibe-check" agent to ensure alignment and prevent scope creep

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🧠 Vibe Check MCP

The Most Widely-Deployed Feedback Layer in the MCP Ecosystem

Used in 1,000+ real workflows.
Featured across 10+ orchestration platforms.
6.5K+ developers already trust it to prevent agentic cascade errors.

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What is Vibe Check?

Vibe Check is a metacognitive layer that keeps AI coding agents honest. It pauses the agent at key moments, challenges shaky assumptions and records what worked (or failed) so the next run is smarter. Think of it as the agent's inner rubber duck—always nudging the conversation back to the user's actual needs.

TL;DR: Vibe Check makes AI coding agents more resilient and aligned by enforcing moments of reflection.

The Problem: Pattern Inertia

LLMs often follow the first solution they imagine. Once that pattern takes hold they elaborate on it even if it drifts from the original goal. Without an external nudge the agent seldom questions its direction, leading to misalignment, overengineering and wasted cycles.

Key Features

  • vibe_check – pattern interrupt tool using the learnlm-2.0-flash-experimental model (with automatic fallback to gemini-2.5-flash and gemini-2.0-flash) for up to a 1M token context window.
  • vibe_learn – records mistakes, preferences and successes to build a rich learning history that feeds back into vibe_check.
  • Large context awareness – the full learning log is summarized and included in prompts so the model can spot recurring patterns and reinforce successful approaches.

These two tools feed each other. vibe_check interrupts questionable plans, vibe_learn captures the lesson, and the growing log informs the next vibe_check call via the model's 1M token context window.

[vibe_check] <----> [vibe_learn]
      ^                |
      |________________|

The more your agent works, the more context Vibe Check has to keep it on the right path.

Installation

# Clone and install
git clone https://github.com/PV-Bhat/vibe-check-mcp-server.git
cd vibe-check-mcp-server
npm install
npm run build

This project targets Node 20+. If you see a TypeScript error about a duplicate require declaration when building with Node 20.19.3, ensure your dependencies are up to date (npm install) or use the Docker setup below which handles the build automatically.

Create a .env file with your API key:

GEMINI_API_KEY=your_gemini_api_key

Start the server:

npm start

Docker

The repository includes a helper script for one-command setup. It builds the image, saves your GEMINI_API_KEY and configures the container to start automatically whenever you log in:

bash scripts/docker-setup.sh

This script:

  • Creates ~/vibe-check-mcp for persistent data
  • Builds the Docker image and sets up docker-compose.yml
  • Prompts for your API key and writes ~/vibe-check-mcp/.env
  • Installs a systemd service (Linux) or LaunchAgent (macOS) so the container starts at login
  • Generates vibe-check-tcp-wrapper.sh which proxies Cursor IDE to the server

After running it, open Cursor IDE → Settings → MCP and add a new server of type Command pointing to:

~/vibe-check-mcp/vibe-check-tcp-wrapper.sh

See Automatic Docker Setup for full details.

If you prefer to run the commands manually:

docker build -t vibe-check-mcp .
docker run -e GEMINI_API_KEY=your_gemini_api_key -p 3000:3000 vibe-check-mcp

Integrating with Claude Desktop

Add to claude_desktop_config.json:

"vibe-check": {
  "command": "node",
  "args": ["/path/to/vibe-check-mcp/build/index.js"],
  "env": { "GEMINI_API_KEY": "YOUR_GEMINI_API_KEY" }
}

Agent Prompting Essentials

In your agent's system prompt make it clear that vibe_check is a mandatory pattern interrupt. Always pass the full user request and specify the current phase (planning, implementation, or review). After correcting a mistake, log it with vibe_learn so the system can recognize it next time.

Example snippet:

As an autonomous agent you will:
1. Call vibe_check after planning and before major actions.
2. Provide the full user request and your current plan.
3. Record resolved issues with vibe_learn so future checks get smarter.

When to Use Each Tool

ToolPurpose
🛑 vibe_checkChallenge assumptions and prevent tunnel vision
🔄 vibe_learnCapture mistakes, preferences and successes

Documentation

To-do List

  • Add in integration for OpenRouter Keys
  • Repomix access to pass repositories to VC
  • Agents.md addendum to improve plug-and-play integration

Contributing

Contributions are welcome! See CONTRIBUTING.md.

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License

MIT

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