MCP server · Security

mcp-pin MCP server

Checks that the tools your AI uses are still the same ones you approved, and blocks the session if they changed.

Security For it and development Security

mcp-pin is a small helper that sits between your AI app and the other MCP servers you have added. It remembers exactly what each server's tools looked like when you approved them, and it checks again every time you connect. It is handy for anyone who has clicked Approve on an MCP server and never looked at it again.

What is an MCP server? The 30-second version

On its own, your AI can only chat with you. An MCP server is a small helper program that gives your AI a new skill or a connection to another app, so it can look things up or do things for you. mcp-pin is itself an MCP server, and it also stands in front of your other MCP servers. When your AI asks mcp-pin a question, mcp-pin checks its records and answers, instead of talking to the outside world.

What this MCP server does

You add mcp-pin to your AI app the same way you add any other MCP server. Then you can ask your AI things like whether a public server's tools have changed recently, or which of your own servers is waiting for your review. mcp-pin looks this up in its own records and in a public log it keeps, and hands back a short answer. It never repeats the actual text of a changed tool description, because that text could be a trick aimed at your AI. All four of its tools only read; they never change anything.

What you can do with it

Check whether a public MCP server's tool list has changed, and when
See which of your own servers are pinned and whether any change is waiting for review
Find out what kind of change is waiting, such as a new instruction or a new field
Get the exact setup steps for protecting servers in Claude Code, Cursor, Codex and VS Code
Ask these questions from inside your AI chat instead of switching to a terminal

Try asking your AI

“Has the tool list for this public MCP server changed recently?”
“Which of my pinned servers has a change waiting for review?”
“What kind of change is waiting on my filesystem server?”
“How do I protect my MCP servers in Cursor?”

What it gives back to you

You get short, plain answers in your chat. For a public server you get dates, counts and hashes, plus a simple yes or no on whether anything changed. For your own servers you get a list of names and a note about which one needs your review. It does not show you the changed wording itself, only labels like new instruction or new field.

Before you start

What you need

Node.js 20 or newer on your computer
An AI app that supports MCP servers, such as Claude Desktop or Cursor
mcp-pin added to that app as an MCP server (the README gives the exact setup)

Good to know

This server only reads and answers questions, but the wider mcp-pin tool it belongs to can block your AI sessions when a server's tools change, so you may need to review and approve changes in a terminal before things work again.

Install it with your AI

Add mcp-pin MCP server to your AI, no technical skills needed

You don't install anything by hand. You copy one prompt, paste it into an AI that can work on your computer, and it checks, installs and connects the server for you, asking you when it needs something.

Sign in to get the install prompt

Members get a ready-made prompt that lets the Claude desktop app check mcp-pin MCP server, install it and connect it for them, step by step. You don't need any technical skills: you copy, paste and answer a few questions. Your connected AI can also find and install any of the 4,609 MCP servers here for you.