A **Model Context Protocol (MCP)** server that charges AI agents per-call via the **x402 micropayment protocol** (USDC on Base). Agents pay **$0.05 USDC** per tool call — no API keys, no subscriptions, just pay-per-use crypto. ``` Agent → POST /mcp/tools/call (no payment) ← 402 + pricing payload (how much, where to pay)