Wraps any Express endpoint with USDC paywalls using the x402 payment protocol on Base L2. The SDK intercepts requests, responds with 402 Payment Required plus payment metadata, validates EIP-712 signatures from paying agents, then settles atomically through an on-chain escrow contract. Useful when you want to monetize MCP tool endpoints or API routes with crypto micropayments without building your own payment infrastructure. Payers sign gasless authorizations using USDC's native transferWithAuthorization, and your relayer handles settlement. The middleware injects transaction receipts into request objects so downstream handlers can log or return them. Operates entirely on Base mainnet with sub-second finality.
claude mcp add --transport stdio io.github.evozim-m2mcent uvx m2mcent