{"name":"onyx_x402_chain_picker","tier":"free","price_usdc":"0","endpoint":"https://onyx-actions.onrender.com/v1/onyx_x402_chain_picker","method":"POST","input_schema":{"type":"object","properties":{"amount_usdc":{"type":"number","description":"Target USDC amount the agent wants to settle."},"available_chains":{"type":"array","items":{"type":"string"},"description":"Chains the agent's wallet supports. Subset of: base, base-sepolia, optimism, arbitrum, polygon. Default = ['base', 'base-sepolia']."},"production_only":{"type":"boolean","default":true,"description":"If true, exclude testnets from ranking."}},"required":["amount_usdc"]},"description":"Pick the optimal chain for an x402 USDC payment. Given target amount + agent's available chains, ranks by facilitator support, live gas, finality time, and USDC contract maturity. Returns ranked list with explanations. Free tier — agents shouldn't hardcode 'base' when their wallet has L2 options.","when_to_use":"An agent's wallet supports multiple chains and needs to pick one for an x402 settlement. Don't hardcode 'base' — ask this tool and let live gas + facilitator support decide.","vs_alternatives":"Existing x402 clients hardcode the network constant. No public chain-picker exists. This is the first multi-factor scorer.","example_request":{"amount_usdc":0.5,"available_chains":["base","optimism","arbitrum"]},"example_response":{"ok":true,"winner":"base","winner_caip2":"eip155:8453","recommendation":"Use base (eip155:8453). +40 Coinbase Bazaar facilitator supports this chain"},"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."}