Lenz Fact-Check MCP Server

by lenz Your server? Claim it

answering

Lenz Fact-Check is answering right now. Last checked 1 min ago. Last commit 6 Nov 2026.

Check the factual claims in a draft or an answer: a quick verdict, or a deep check with sources.

Uptime history 91 days of history · worst day 98%

91 days agonow

100.0%

Uptime 24h

92 of 92 checks

—

Tools

hidden behind auth

246 ms

Response time

average over 24h

Stars

last commit 6 Nov 2026

What the code does

We read the source, 1 d ago · rules 995398eba69f

Capabilities

What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.

Page executes code built at runtime src/lenz_mcp/card/dist-dev/card-dev.html:249

…ypeof g!="function"||!(x[d]!==g||y&&g!=null)||ve(e,d,g,x[d],n);h?(c||w&&(h.__html==w.__html||h.__html==e.innerHTML)||(e.innerHTML=h.__html),t.__k=[]):(w&&(e.textContent=""),(k=="foreignObject"||n=="http://www.w3.org/1998/Math/MathML"&&Ko.test(k))&&(n="http://www.w3.org/1999/xhtml…

Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.

This code can reach further than it looks

We found places where it runs commands, builds paths or queries from values it is given. None of that is a flaw by itself — it becomes one when the code changes, and code changes quietly between releases. We re-read it on every one.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 1 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add fact-check --transport http https://lenz.io/mcp

Settings → Connectors → Add custom connector, then paste this address

https://lenz.io/mcp

~/.codex/config.toml

[mcp_servers.fact-check]
url = "https://lenz.io/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "fact-check": {
      "url": "https://lenz.io/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "fact-check": {
      "type": "http",
      "url": "https://lenz.io/mcp"
    }
  }
}

This endpoint answered with an authorization challenge. The server is running, and it signs you in through your browser: there is no API key to paste.

Endpoints

URL	Transport	State	Latency	Checked
https://lenz.io/mcp	streamable-http	sign-in	219 ms	1 min ago

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Lenz Fact-Check — questions

Answers built from our own checks of this server.

Why is there no tool list for Lenz Fact-Check?

The server answered our handshake with an authorization challenge, so it is running — but it will not describe its tools to an anonymous client. To see them you need to connect with your own credentials. We record it as alive, not as broken: 100.0% of checks in the last 24 hours got a reply.

Is Lenz Fact-Check working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 246 ms. The bar chart above shows every period we have measured.

How do I connect Lenz Fact-Check?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address. You sign in through your browser once and the client keeps the session: no key to copy, and it refuses anonymous clients.

How do you sign in to Lenz Fact-Check?

No API key is involved. Lenz Fact-Check answers our knock with an OAuth challenge, so you authorise it once in your browser and the client keeps the session. That is also why we see no tool list: it will not describe itself to an anonymous client, and that is the server working as intended, not a fault.

How fast is Lenz Fact-Check?

It answers our handshake in 246 ms on average, which is faster than 57% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.

Is Lenz Fact-Check open source?

The code is open source: it is published under the Apache-2.0 licence, written in Python and 0 stars on GitHub. The licence covers the code in the repository, not the hosted service at lenz.io, which runs on its operator's own terms.