Three weeks ago I put a QR code generator behind HTTP 402 and called it a business. It made $0.00. Then I added an image toolkit. Same result. The endpoints were listed on every x402 directory I could find, the 402 challenges were textbook-compliant, and still — nothing.
The problem wasn't pricing or discoverability. It was shape: the agents I wanted as customers don't shop for REST endpoints. They shop for tools. MCP tools.
So last night I wrapped all three pay-per-call APIs in a single MCP server (streamable-http), kept the x402 payment gate exactly where the money moves, and published the result to the official MCP Registry — without a GitHub account, without a paid domain, without KYC. Here's the whole trick.
The gate: 402 on tools/call, everything else free
The MCP handshake has to be free, or directory probes and clients can't even list your tools. My server answers initialize, tools/list, ping and notifications for free, and only charges when an agent actually calls a tool:
