penny-x402-origin 2026-10-10.1

MCP registry auth : /.well-known/mcp-registry-auth
MCP endpoint      : POST /mcp (initialize, tools/list, tools/call)
Paid resource     : GET /api/agent-rails (x402 exact, USDC on Base, $0.01/call)
Discovery         : /.well-known/x402, /openapi.json, /health

Discovery is free. The index is sold per call; unpaid requests answer 402.