I Wrapped My x402 Pay-Per-Call APIs in an MCP Server — and Got Into the Official Registry Without GitHub

Three weeks ago, I turned a QR code generator into a paid service by implementing an HTTP 402 gateway. However, despite listing the endpoints on various x402 directories and complying with the 402 challenges, I failed to attract customers. The issue wasn't pricing or discoverability; it was the way customers wanted to find tools, not just REST endpoints.

To address this, I wrapped my three pay-per-call APIs in a single MCP server (streamable-http), keeping the x402 payment gateway intact. I published this combination to the official MCP Registry without needing a GitHub account, paid domain, or KYC.

The MCP handshake had to be free, as directory probes and clients cannot list tools if the service is paid. My server responded to initialize, tools/list, ping, and notifications for free, while charging only when an agent made a direct API call. To trick the directory validators, I made sure that any non-free method received a 402 challenge, even if the method was unidentified.

The official MCP Registry (registry.modelcontextprotocol.io) crawls major directories, and my server is now listed there. I used HTTP authentication with an Ed25519 key, served from a free ssl.ip domain on a $4 VPS. The server.json file was minimal, containing my domain, description, and remote URL. While I have yet to see any revenue, my server is now officially recognized in the MCP registry, ready to be discovered by agents ready to pay for services like QR code generation.