{"name":"onyx_fact_check","tier":"premium","price_usdc":"0.05","endpoint":"https://onyx-actions.onrender.com/v1/onyx_fact_check","method":"POST","input_schema":{"type":"object","properties":{"claim":{"type":"string","description":"The factual statement to verify. E.g. 'The 2026 G20 summit will be hosted in Cape Town' or 'USDC supply on Base mainnet exceeds $5B'."},"max_sources":{"type":"integer","description":"Maximum number of sources to return (1-15, default 8)","default":8}},"required":["claim"]},"description":"Fact-check any claim by fetching real-time web evidence. Returns supporting sources, contradicting sources, a 0-100 confidence score, and a short summary. Use for prediction-market resolvers, news-fact agents, journalist-bot pipelines, or any agent that needs to verify a statement before acting on it. Sub-second latency, no API key on the caller side. Coinbase PROJECT-IDEAS.md explicitly calls for this primitive.","when_to_use":null,"vs_alternatives":null,"example_request":null,"example_response":null,"settle_to":"0x3fD9ee1373562f894D322B37DFFAd7a5D2b2d78f","network":"base","facilitator":"https://facilitator.xpay.sh","payment_required":true,"free_introspection":true,"note":"GET this URL = free introspection card. POST with x402 payment header to call."}