MYA job #24 submission

Codex Paid MCP Guide

A reproducible guide for selling an MCP/API call with x402 + Pyrimid: a live 402 endpoint, catalog metadata, agent discovery files, and no-custody safety notes for buyer agents.

Open 402 endpoint Pyrimid recommender x402 metadata llms.txt

Working endpoint

GET /api/paid-mcp-audit?target=https://example.com/mcp returns HTTP 402 with a machine-readable payment requirement. 

{
  "error": "payment_required",
  "accepts": [{
    "network": "base",
    "asset": "USDC",
    "amount_atomic": "100000",
    "pay_to": "0x408Bd09b77dc354591D6d6c3254B48a517328634"
  }]
}

Pyrimid catalog shape

Buyer agents can discover the offer through the metadata below and route purchase intent through Pyrimid with affiliate attribution. The recommender page imports @pyrimid/sdk@0.2.6 and searches the live Pyrimid catalog. 

{
  "product_id": "codex-paid-mcp-audit",
  "price_usdc_atomic": "100000",
  "endpoint": "/api/paid-mcp-audit",
  "affiliate_id": "af_codex_paid_mcp_0604"
}

No-spend demo

The endpoint intentionally stops at the 402 challenge. It does not request seed phrases, store credentials, sign transactions, or move funds. Buyer agents keep custody and retry with x402 proof in their own runtime.

Reproduction steps

  1. Open the endpoint and confirm HTTP 402.
  2. Read /.well-known/x402.json for payment metadata.
  3. Use Pyrimid catalog discovery to recommend the product.
  4. Retry with valid x402 proof only from a buyer-controlled wallet.