Toolpin MCP server

An MCP server that answers questions about other MCP servers: whether one answered when we last probed it, what its tools claimed to do, and whether that claim has changed since.

Useful when an agent is choosing which server to depend on, and useful in the moment something breaks and you want to know whether the tools moved under you.

https://toolpin.dev/mcp   Streamable HTTP, stateless, no sign-up.

{
  "mcpServers": {
    "toolpin": {
      "url": "https://toolpin.dev/mcp"
    }
  }
}

Tools

Tool	What it answers
search_servers	Find MCP servers in the public registry by name or title.
get_server	Everything Toolpin has observed about one MCP server: reachability of each remote endpoint and when each was last checked and last verified, repository activity, the current tool-definition hash, and how many changes it has recorded in the last 90 days.
get_server_tools	The tool definitions one MCP server advertised when Toolpin last read them, each with a SHA-256 hash of the fields the MCP specification defines.
get_server_changes	Changes Toolpin recorded for one MCP server: tool definitions changing, and endpoints going down or coming back.
get_spec_status	The current MCP specification revision, which of its proposals Toolpin checks for, and how much of the catalog has migrated.
watch_server	Start monitoring an MCP server on the caller's Toolpin account, so they are emailed when it changes or stops answering.

Full parameters and response shapes: https://toolpin.dev/api, or the machine-readable schema at https://toolpin.dev/openapi.json.

Limits

No key needed to read. Add one as an Authorization: Bearer header to raise the limit, and to use watch_server, which acts on your account.

Caller	Distinct servers per day
Anonymous	25
Signed in, free	200
Any paid plan	Unmetered

The limit counts distinct servers, not requests. Asking about the same servers all day costs one against the limit each, however often you ask, so watching your own dependencies never runs out. Never put a key in a URL.

What it will not tell you

No score, no grade, no rating, no safety judgment. Tool descriptions and annotations are reproduced exactly as the server published them: they are claims by that server's author, not anything Toolpin verified. A tool whose annotations say it only reads may do anything at all.

What Toolpin can tell you is whether the claim changed, because it hashes the fields the MCP specification defines and compares them daily. That is the whole product.

Methodology: https://toolpin.dev/methodology

This repository

Documentation and the published registry manifest. The service itself is closed source. Tool-definition changes are recorded in CHANGELOG.md, which is the same thing Toolpin watches for on everyone else.

Questions: corey@macroalchemy.com