Skip to content

x402 Payment Request Parser

by mk-career-planning · remote · no sign-in to list tools · v0.1.0 · published by GitHub user mk-career-planning

x402 payment-request parser with a limited token list. Does not sign, approve or judge payments.

Final · 1Changes · 1
CompareRegistry entry

4 tools: 1 do something that can't be undone, 1 change things and 2 only read.

Scanned Oct 21, 2026

1 check matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http x402-safety-kit https://x402-safety-kit-production.mk-career-planning.workers.dev/mcp

Findings

Matches of fixed checks, with the text they matched.

1 warn
  • Warnx402_parse_payment_request

    The server marks "x402_parse_payment_request" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".

    Matched text

    annotations: {"readOnlyHint":true,"idempotentHint":true,"openWorldHint":false}; The name "x402_parse_payment_request" says "payment": a word that usually means money moves, which cannot be taken back.

    What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

4 tools

Can't be undone 1Claude Code: ask
  • x402_parse_payment_requestFree.1 finding

    Why it is in this group

    • The name "x402_parse_payment_request" says "payment": a word that usually means money moves, which cannot be taken back.
    • The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.

    Findings

    • Warn

      The server marks "x402_parse_payment_request" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".

      Matched text

      annotations: {"readOnlyHint":true,"idempotentHint":true,"openWorldHint":false}; The name "x402_parse_payment_request" says "payment": a word that usually means money moves, which cannot be taken back.

      What this check looks for
    Description, as the server wrote it
    Free. Decode one x402 v2 payment request (base64 PAYMENT-REQUIRED header, PaymentRequired JSON or MCP tool result) and list every accepts option with exact atomic and decimal amounts. Token addresses are compared with a limited reference list. status: parsed, ambiguous (options differ in recipient, network or amount; none is chosen), malformed or unsupported. Does not verify the merchant, authorize a transfer, assess fraud risk, or guarantee any payment. URLs in the input are never fetched.

    Annotations the server declares

    • readOnlyHint: true
    • openWorldHint: false
    • idempotentHint: true
Changes things 1Claude Code: ask
  • x402_known_assetsFree.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    • The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
    Description, as the server wrote it
    Free. The limited reference list this server compares token addresses with: known assets (network, contract, symbol, decimals) with sources and check dates, known CAIP-2 networks, scheme names from the x402 specs, and payment flows. A table match is not proof that an asset or a merchant is genuine.

    Annotations the server declares

    • readOnlyHint: true
    • openWorldHint: false
    • idempotentHint: true
Only reads 2Claude Code: allow
  • catalogList the tools of this server with prices, data sources, licensing, daily limits and data freshness.No findings

    Why it is in this group

    • The description's first verb is "list": a word for reading.
    Description, as the server wrote it
    List the tools of this server with prices, data sources, licensing, daily limits and data freshness.

    Annotations the server declares

    • readOnlyHint: true
  • get_receiptRe-fetch the stored result of a settled paid call by its receipt_id, for when the response was lost after payment.No findings

    Why it is in this group

    • The name "get_receipt" says "get": a word for reading.
    Description, as the server wrote it
    Re-fetch the stored result of a settled paid call by its receipt_id, for when the response was lost after payment. Free. Unknown or unsettled receipt ids return RECEIPT_NOT_FOUND. Results are kept for 90 days after settlement.

    Annotations the server declares

    • readOnlyHint: true

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 0.1.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http x402-safety-kit https://x402-safety-kit-production.mk-career-planning.workers.dev/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__x402-safety-kit__catalog",
      "mcp__x402-safety-kit__get_receipt"
    ],
    "ask": [
      "mcp__x402-safety-kit__x402_parse_payment_request",
      "mcp__x402-safety-kit__x402_known_assets"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as x402-safety-kit. Review it before you use it.