x402 Doctor MCP Server

by twelvepermissions Your server? Claim it

answering

x402 Doctor is answering right now. Last checked 11 min ago. It exposes 3 tools. Last commit 8 Sep 2026.

Diagnose x402 seller endpoints: what is wrong with your 402 challenge, and how to fix it.

Uptime history 70 days of history · worst day 93%

70 days agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

164 ms

Response time

average over 24h

Stars

last commit 8 Sep 2026

Nothing serious here today

Today is the operative word: we check x402 Doctor every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 11 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add x402-doctor --transport http https://x402-doctor.tsharpe.workers.dev/mcp

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

https://x402-doctor.tsharpe.workers.dev/mcp

~/.codex/config.toml

[mcp_servers.x402-doctor]
url = "https://x402-doctor.tsharpe.workers.dev/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "x402-doctor": {
      "url": "https://x402-doctor.tsharpe.workers.dev/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "x402-doctor": {
      "type": "http",
      "url": "https://x402-doctor.tsharpe.workers.dev/mcp"
    }
  }
}

Available tools 3

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

checks

list_checks

The whole rule table. Knowing what was NOT checked is part of knowing what a clean result means.

explain

explain_defect

Full explanation of one rule by id — what it checks, why it matters, how to fix it, and where the rule came from. Use when you want the reasoning without re-probing.

probe

probe_x402_endpoint

Probe an x402 seller endpoint and report what it observes about it. Performs the handshake a paying client would: GET with no X-PAYMENT header, then checks the 402 challenge against 16 rules. Every finding says whether the rule comes from the x402 spec or from an observed facilitator rejection. Reports status "healthy" (nothing to report), "advisories" (only warn/info findings — the endpoint works), "defects_found" (at least one error-severity finding), "not_x402" or "unreachable".

Endpoints

URL	Transport	State	Latency	Checked
https://x402-doctor.tsharpe.workers.dev/mcp	streamable-http	answering	82 ms	11 min ago

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x402 Doctor — questions

Answers built from our own checks of this server.

What can x402 Doctor do?

It exposes 3 tools, read directly from the server on our last check. Among them: explain_defect, list_checks, probe_x402_endpoint. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is x402 Doctor working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 164 ms. The bar chart above shows every period we have measured.

How do I connect x402 Doctor?

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.

Does x402 Doctor need an API key?

No. x402 Doctor completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 3 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is x402 Doctor?

It answers our handshake in 164 ms on average, which is faster than 86% of all working MCP servers we measure. That puts it in the quick quarter of the ecosystem. The comparison comes from our own checks across the whole registry, every 15 minutes.

Is x402 Doctor open source?

We cannot say either way: written in JavaScript, 0 stars on GitHub and 1 open issue, but we could not determine the licence, and without one the code is not open source by default.