Paid: a central-bank rate decision card. $0.10 USDC on Base (x402 v2, exact). An unpaid call returns JSON-RPC error 402 whose data is the x402 PaymentRequired (also base64 in data.payment_required and the PAYMENT-REQUIRED header). Pay by retrying the same tools/call with the PaymentPayload in params._meta["x402/payment"], or with header PAYMENT-SIGNATURE: . The receipt comes back in result._meta["x402/payment-response"] and the PAYMENT-RESPONSE header. Policy ids: BOE, FED, ECB, BOJ, RBA, BOC, SNB. Others return 404 (no charge).