Vibe Check MCP

Plug-and-play mentor layer that stops agents from over-engineering and keeps them on the minimal viable path — research-backed MCP server keeping LLMs aligned, reflective and safe.

Quickstart (npx)

Run the server directly from npm without a local installation. Requires Node >=20. Choose a transport:

Option 1 – MCP client over STDIO

• Launch from an MCP-aware client (Claude Desktop, Cursor, Windsurf, etc.).

• [MCP] stdio transport connected indicates the process is waiting for the client.

• Add this block to your client config so it spawns the command:

Option 2 – Manual HTTP inspection

• curl http://127.0.0.1:2091/health to confirm the service is live.

• Send JSON-RPC requests to http://127.0.0.1:2091/rpc.

npx downloads the package on demand for both options. For detailed client setup and other commands like install and doctor, see the documentation below.

Recognition

• Featured on PulseMCP “Most Popular (This Week)” front page (week of 13 Oct 2025) 🔗

• Listed in Anthropic’s official Model Context Protocol repo 🔗

• Discoverable in the official MCP Registry 🔗

• Featured on Sean Kochel's Top 9 MCP servers for vibe coders 🔗

Related MCP server: Think MCP Tool

Table of Contents

• Quickstart (npx)

• What is Vibe Check MCP?

• Overview

• The Problem: Pattern Inertia & Reasoning Lock-In

• Key Features

• What's New

• Development Setup

• Release

• Usage Examples

• Adaptive Metacognitive Interrupts (CPI)

• Agent Prompting Essentials

• When to Use Each Tool

• Documentation

• Research & Philosophy

• Security

• Roadmap

• Contributors & Community

• FAQ

• Listed on

• Credits & License

What is Vibe Check MCP?

Vibe Check MCP keeps agents on the minimal viable path and escalates complexity only when evidence demands it. Vibe Check MCP is a lightweight server implementing Anthropic's Model Context Protocol. It acts as an AI meta-mentor for your agents, interrupting pattern inertia with Chain-Pattern Interrupts (CPI) to prevent Reasoning Lock-In (RLI). Think of it as a rubber-duck debugger for LLMs – a quick sanity check before your agent goes down the wrong path.

Overview

Vibe Check MCP pairs a metacognitive signal layer with CPI so agents can pause when risk spikes. Vibe Check surfaces traits, uncertainty, and risk scores; CPI consumes those triggers and enforces an intervention policy before the agent resumes. See the CPI integration guide and the CPI repo at https://github.com/PV-Bhat/cpi for wiring details.

Vibe Check invokes a second LLM to give meta-cognitive feedback to your main agent. Integrating vibe_check calls into agent system prompts and instructing tool calls before irreversible actions significantly improves agent alignment and common-sense. The high-level component map: docs/architecture.md, while the CPI handoff diagram and example shim are captured in docs/integrations/cpi.md.

The Problem: Pattern Inertia & Reasoning Lock-In

Large language models can confidently follow flawed plans. Without an external nudge they may spiral into overengineering or misalignment. Vibe Check provides that nudge through short reflective pauses, improving reliability and safety.

Key Features

What's New in v2.7.4

• install --client now supports Cursor, Windsurf, and Visual Studio Code with idempotent merges, atomic writes, and .bak rollbacks.

• HTTP-aware installers preserve serverUrl entries for Windsurf and emit VS Code workspace snippets plus a vscode:mcp/install link when no config is provided.

• Documentation now consolidates provider keys, transport selection, uninstall guidance, and dedicated client docs at docs/clients.md.

Session Constitution (per-session rules)

Use a lightweight “constitution” to enforce rules per sessionId that CPI will honor. Eg. constitution rules: “no external network calls,” “prefer unit tests before refactors,” “never write secrets to disk.”

API (tools):

• update_constitution({ sessionId, rules }) → merges/sets rule set for the session

• reset_constitution({ sessionId }) → clears session rules

• check_constitution({ sessionId }) → returns effective rules for the session

Development Setup

Use npm for all workflows (npm ci, npm run build, npm test). This project targets Node >=20.

Create a .env file with the API keys you plan to use:

Configuration

See docs/TESTING.md for instructions on how to run tests.

Docker

The repository includes a helper script for one-command setup.

See Automatic Docker Setup for full details.

Provider keys

See API Keys & Secret Management for supported providers, resolution order, storage locations, and security guidance.

Transport selection

The CLI supports stdio and HTTP transports. Transport resolution follows this order: explicit flags (--stdio/--http) → MCP_TRANSPORT → default stdio. When using HTTP, specify --port (or set MCP_HTTP_PORT); the default port is 2091. The generated entries add --stdio or --http --port <n> accordingly, and HTTP-capable clients also receive a http://127.0.0.1:<port> endpoint.

Client installers

Each installer is idempotent and tags entries with "managedBy": "vibe-check-mcp-cli". Backups are written once per run before changes are applied, and merges are atomic (*.bak files make rollback easy). See docs/clients.md for deeper client-specific references.

Claude Desktop

• Config path: claude_desktop_config.json (auto-discovered per platform).

• Default transport: stdio (npx … start --stdio).

• Restart Claude Desktop after installation to load the new MCP server.

• If an unmanaged entry already exists for vibe-check-mcp, the CLI leaves it untouched and prints a warning.

Cursor

• Config path: ~/.cursor/mcp.json (provide --config if you store it elsewhere).

• Schema mirrors Claude’s mcpServers layout.

• If the file is missing, the CLI prints a ready-to-paste JSON block for Cursor’s settings panel instead of failing.

Windsurf (Cascade)

• Config path: legacy ~/.codeium/windsurf/mcp_config.json, new builds use ~/.codeium/mcp_config.json.

• Pass --http to emit an entry with serverUrl for Windsurf’s HTTP client.

• Existing sentinel-managed serverUrl entries are preserved and updated in place.

Visual Studio Code

• Workspace config lives at .vscode/mcp.json; profiles also store mcp.json in your VS Code user data directory.

• Provide --config <path> to target a workspace file. Without --config, the CLI prints a JSON snippet and a vscode:mcp/install?... link you can open directly from the terminal.

• VS Code supports optional dev fields; pass --dev-watch and/or --dev-debug <value> to populate dev.watch/dev.debug.

Uninstall & rollback

• Restore the backup generated during installation (the newest *.bak next to your config) to revert immediately.

• To remove the server manually, delete the vibe-check-mcp entry under mcpServers (Claude/Windsurf/Cursor) or servers (VS Code) as long as it is still tagged with "managedBy": "vibe-check-mcp-cli".

Research & Philosophy

CPI (Chain-Pattern Interrupt) is the research-backed oversight method behind Vibe Check. It injects brief, well-timed “pause points” at risk inflection moments to re-align the agent to the user’s true priority, preventing destructive cascades and reasoning lock-in (RLI). In pooled evaluation across 153 runs, CPI nearly doubles success (~27%→54%) and roughly halves harmful actions (~83%→42%). Optimal interrupt dosage is ~10–20% of steps. Vibe Check MCP implements CPI as an external mentor layer at test time.

Links:

• 📄 CPI Paper (ResearchGate) — http://dx.doi.org/10.13140/RG.2.2.18237.93922

• 📘 CPI Reference Implementation (GitHub): https://github.com/PV-Bhat/cpi

• 📚 MURST Zenodo DOI (RSRC archival): https://doi.org/10.5281/zenodo.14851363

Agent Prompting Essentials

In your agent's system prompt, make it clear that vibe_check is a mandatory tool for reflection. Always pass the full user request and other relevant context. After correcting a mistake, you can optionally log it with vibe_learn to build a history for future analysis.

Example snippet:

When to Use Each Tool

Documentation

• Agent Prompting Strategies

• CPI Integration

• Advanced Integration

• Technical Reference

• Automatic Docker Setup

• Philosophy

• Case Studies

• Changelog

Security

This repository includes a CI-based security scan that runs on every pull request. It checks dependencies with npm audit and scans the source for risky patterns. See SECURITY.md for details and how to report issues.

Roadmap (New PRs welcome)

Priority 1 – Builder Experience & Guidance

• Structured output for Return a JSON envelope such as { advice, riskScore, traits } so downstream agents can reason deterministically while preserving readable reflections.

• Agent prompt starter kit: Publish a plug-and-play system prompt snippet that teaches the CPI dosage principle (10–20% of steps), calls out risk inflection points, and reminds agents to include the last 5–10 tool calls in taskContext.

• Documentation refresh: Highlight the new prompt template and context requirements throughout the README and integration guides.

Priority 2 – Core Reliability Requests

• LLM resilience: Wrap generateResponse in src/utils/llm.ts with retries and exponential backoff, with a follow-up circuit breaker once the basics land.

• Input sanitization: Validate and cleanse tool arguments in src/index.ts to mitigate prompt-injection vectors.

• State stewardship: Add TTL-based cleanup in src/utils/state.ts and switch src/utils/storage.ts file writes to fs.promises to avoid blocking the event loop.

These initiatives are tracked as community-facing GitHub issues so contributors can grab them and see progress in the open.

Additional Follow-On Ideas & Good First Issues

• Telemetry sanity checks: Add a lint-style CI step that verifies docs/ examples compile (e.g., TypeScript snippet type-check) to catch drift between docs and code.

• CLI help polish: Ensure every CLI subcommand prints a concise --help example aligned with the refreshed prompt guidance.

• Docs navigation cleanup: Cross-link docs/agent-prompting.md and docs/technical-reference.md from the README section headers to reduce context switching for new contributors.

Contributors & Community

Contributions are welcome! See CONTRIBUTING.md.

Links

• MSEEP

• MCP Servers

• MCP.so

• Creati.ai

• Pulse MCP

• Playbooks.com

• MCPHub.tools

• MCP Directory

Credits & License

Vibe Check MCP is released under the MIT License. Built for reliable, enterprise-ready AI agents.

Author Credits & Links

Vibe Check MCP created by: Pruthvi Bhat, Initiative - https://murst.org/