Use before paying any x402 invoice: decodes a base64 PAYMENT-REQUIRED header (query ?header= or JSON body {header}) and checks scheme exact, Base mainnet, Base USDC asset, payTo (EOA/contract/EIP-7702), human amount, timeout; returns verdict ok/warn/fail with reasons. Errors: 400 invalid header. Read-only; never signs or pays.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.02 USDC | 0xa26f...8147 |