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PreFlight Transaction Pre-Sign Safety Checker
x402
PreFlight Transaction Pre-Sign Safety Checker is a paid API for AI agents from meryol-agenticmarket-x402.hf.space, paid per call via x402, $0.015/call, status unknown (last checked 2026-09-13).
Analyzes EVM transaction calldata before signing to detect risk flags, decode intent, and recommend whether to approve or decline
Price / call$0.015
Success—
StatusUnknown
How this service works
Pre-trade & pre-sign checks for autonomous agents: everything an agent verifies BEFORE signing a transaction — token due diligence, calldata red-flag decoding, oracle freshness, holder concentration, bridge routing with executable calldata, cross-venue perp funding, gas and price sanity checks. EVM chains: Ethereum, Base, Arbitrum, Optimism.
Output
A JSON object containing the decoded function selector and signature, a plain-English explanation of what the transaction does, a list of specific risk flags (e.g. unlimited_token_approval, approval_to_unverified_contract), an overall verdict (e.g. 'danger'), a recommended action (e.g. 'decline'), and the target contract address and chain.
Example use cases
Wallet security check before signing
“I'm about to sign a transaction on Ethereum but I'm not sure what it does. Can you decode the calldata and tell me if there are any red flags? The transaction is going to 0x68b3465833fb72B5A828cCEDA4284a1E6c7E19CA with data 0xa4d66daf and I want to know if it's safe to approve.”
Detect unlimited token approval drains
“My agent just flagged an approve() call to an unfamiliar contract address. Decode what's happening and check if this is an unlimited approval that could drain my tokens — I need the risk verdict and your recommendation on whether to sign it or not.”
Pre-trade safety check for bridge routing
“Before my agent executes this cross-chain swap on Arbitrum, run a pre-sign check on the calldata. I want to verify the bridge routing is legitimate, check for any phishing patterns, and get your verdict on whether this transaction is safe to submit.”
Technical details
Endpoint
POSThttps://meryol-agenticmarket-x402.hf.space/tx/explainWhen to prefer
Use this endpoint when an AI agent or wallet needs to evaluate the safety of an EVM transaction BEFORE signing — especially for token approvals, bridge calls, or unfamiliar contract interactions. Prefer this over generic contract explorers when you need a structured risk verdict with actionable recommended_action and decoded argument context, not just ABI decoding.
Side effects
- Unrecognized or non-standard calldata selector returns null decoded_args
- Contract not verified on-chain yields limited context and higher uncertainty
- Unsupported chain returns an error (only Ethereum, Base, Arbitrum, Optimism supported)
- Malformed or truncated calldata may produce incomplete decoding
- Rate limiting or payment failure returns HTTP 402 or 429
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"to": "0xabc...",
"chain": "base",
"notes": [],
"verdict": "danger",
"selector": "0x095ea7b3",
"signature": "approve(address,uint256)",
"risk_flags": [
"unlimited_token_approval",
"approval_to_unverified_contract"
],
"explanation": "This grants type(uint256).max allowance on USDC to 0xabc... which is not source-verified. Common drainer pattern.",
"decoded_args": null,
"what_it_does": "Approve unlimited USDC spend by an unverified router.",
"recommended_action": "decline"
}
}Tags
x402
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