Has this MCP server changed its tools?
Paste a server's address or its registry name. HISTOR — a public, append-only log that watches the MCP servers in public registries — answers from its own signed observations: when it first pinned the tool set, how many times it changed, and what its pattern scan found.
Free · no account · no wallet
What it checks
- When HISTOR first pinned the server's tool set, and since when it has been unchanged.
- How many times the tool set changed, out of how many observations.
- What HISTOR's pattern scan found in the current set, tool by tool.
- A link to the server's page in the log, and the log's signed answer.
What it does not check
HISTOR answers from what it observed and never connects to the address you give. To compare what your own client is served with what everyone gets, run the local WARDEN scan with --histor.
Privacy
HISTOR never fetches the address. For an address it does not know, it counts the host name and the day — nothing else — to decide which servers to watch next.
AI agents buy the same check
This page is free for people. An AI agent gets the same deterministic answer for $0.001 a call over x402 — USDC on Base, no account, no API key:
POST https://modelmarket.dev/x402/histor-checkListed in the Coinbase x402 Bazaar and on x402scan. What an agent pays for is the answer this page shows, byte for byte.
Free for agents too, at a lower rate limit:
POST https://modelmarket.dev/a2mcp/histor-checkQuestions
What is HISTOR?
A transparency log for MCP tool sets, in the spirit of Certificate Transparency: every observation is an entry in an append-only Merkle log with a signed tree head, so a tool set shown to one client and not to others can be noticed.
Why would a server's tools change?
Mostly releases. A change is not an accusation; it is a reason to read the diff before your model reads the new descriptions — the MCP rug-pull diff does that.
Other free checks
x402 payment check
Why a USDC transferWithAuthorization reverts: the signer, the token domain, the window and the seller's terms — and the domain a failing signature was really made for.
MCP rug-pull diff
Two tools/list results of one server — the one you approved and today's. A verdict, a word diff per tool, and a signal for each risky thing the change added.
MCP tool scan (WARDEN)
One tools/list. WARDEN, the open-source MCP firewall, checks every name, description, schema and annotation for prompt injection, exfiltration and credential theft.