{"name":"onyx_x402_spec_lookup","tier":"free","price_usdc":"0","endpoint":"https://onyx-actions.onrender.com/v1/onyx_x402_spec_lookup","method":"POST","input_schema":{"type":"object","properties":{"query":{"type":"string","description":"What to look up: error string ('invalid_exact_evm_payload_authorization_valid_before'), header name ('PAYMENT-SIGNATURE'), status code ('402'), payload field ('nonce'), or feature keyword ('EIP-3009', 'CAIP-2', 'facilitator', 'JWT')."}},"required":["query"]},"description":"Quick-reference into the x402 v2 protocol spec. Look up an error string, HTTP status, header name, payload field, or feature keyword and get the relevant spec snippet plus a plain-English fix. Replaces 30 minutes of spec-grepping with a single call. Free tier — embedded knowledge, no network.","when_to_use":"An agent or developer hit an x402 error, header name, status code, or feature they don't immediately recognize. One call returns the spec snippet + the fix.","vs_alternatives":"x402.org docs are good but require navigation; coinbase/x402 GitHub README is comprehensive but long. This tool returns the EXACT relevant snippet in one shot, machine-readable, suitable for agent decision-making mid-loop.","example_request":{"query":"invalid_exact_evm_payload_authorization_valid_before"},"example_response":{"ok":true,"query":"invalid_exact_evm_payload_authorization_valid_before","match_count":2,"matches":[{"topic":"/verify response shape","spec":"...","fix":"..."},{"topic":"EIP-3009 timing constraints","spec":"...","fix":"..."}]},"settle_to":"0x3fD9ee1373562f894D322B37DFFAd7a5D2b2d78f","network":"base","facilitator":"https://facilitator.xpay.sh","payment_required":false,"free_introspection":true,"note":"GET this URL = free introspection card. POST with x402 payment header to call."}