{"name":"onyx_base_tx_simulator","tier":"metered","price_usdc":"0.10","endpoint":"https://onyx-actions.onrender.com/v1/onyx_base_tx_simulator","method":"POST","input_schema":{"type":"object","properties":{"from_address":{"type":"string","description":"0x-prefixed sender"},"to_address":{"type":"string","description":"0x-prefixed contract or wallet"},"data":{"type":"string","description":"Hex-encoded calldata (default 0x)"},"value_wei":{"type":"string","description":"ETH wei to send (default 0)"},"block":{"type":"string","description":"block tag (latest/pending/0x...) default latest"}},"required":["to_address"]},"description":"Simulate a Base mainnet transaction before sending it. Returns success/revert prediction, the revert reason if any, decoded return data, and an estimated gas figure. Use as a pre-flight check inside a trading agent's tool-call dispatcher — agents should simulate before signing to avoid paying gas on a doomed tx. Direct equivalent of OATP's Solana tx_simulator ($0.20, 1,304 unique paying agents) — Onyx is the first to ship this on Base mainnet at $0.10. Read-only — never submits.","when_to_use":"Use BEFORE signing any Base mainnet transaction with non-trivial value. Catches reverts, decodes revert reasons, projects gas. Saves agents from blowing gas on doomed txs. Read-only — never submits.","vs_alternatives":"OATP charges $0.20 for tx_simulator on Solana. Tenderly/Foundry require infra setup and API keys. Onyx is the first x402-paid Base-native simulator, half OATP price.","example_request":{"from_address":"0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","to_address":"0x4200000000000000000000000000000000000006","data":"0xa9059cbb..."},"example_response":{"success":true,"return_data":"0x000...01","gas_estimate":51234,"elapsed_ms":145},"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."}