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Base Transaction Calldata Preflight Inspector
x402
Base Transaction Calldata Preflight Inspector is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).
Decodes and analyzes EVM calldata for a Base transaction before signing, flagging token transfers, approvals, unlimited spending allowances, and unknown function selectors.
Price / call$0.005
Success—
StatusUnknown
How this service works
Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.
Output
Returns a structured assessment including the decoded activity (e.g. ERC-20 approve, transfer), identity information about the contract, a risk assessment flagging unlimited approvals or unknown selectors, and provenance metadata — all machine-readable so the agent can decide whether to proceed with signing.
Example use cases
Example prompt
“Before I sign this Base transaction to contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 with calldata 0x095ea7b3000000000000000000000000deadbeefdeadbeefdeadbeefdeadbeefdeadbeef ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff and no ETH value, can you decode what it actually does and flag if it's an unlimited token approval?”
Technical details
Endpoint
GEThttps://base-agent-preflight.bytoken2023.workers.dev/v1/x402/base/transaction-intentWhen to prefer
Use this endpoint when an AI agent is about to sign or broadcast a Base network transaction and needs to understand what the calldata actually does before committing — especially for DeFi interactions involving token approvals, transfers, or unfamiliar contract calls. Prefer over generic ABI decoders when you need a risk-oriented assessment with unlimited-approval and unknown-selector flags specific to the Base chain.
Side effects
- Invalid 'to' address format (not a 40-char hex) returns validation error
- Malformed or truncated calldata returns decoding failure
- Unknown function selector returns flagged unknown-selector warning rather than full decode
- Missing required 'to' or 'data' query params returns 400-level error
- Payment not included or insufficient USDC triggers x402 payment required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"network": "eip155:8453",
"product": "evm-transaction-intent",
"assessment": {
"flags": [],
"risk_level": "low",
"risk_score": 0
}
}
}Tags
x402
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