presign-guard explain

x402

presign-guard explain is a paid API for AI agents from presign-guard.fizzl.eu, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-11).

Returns a green/orange/red risk verdict plus a plain-language explanation (in English or Dutch) for a transaction, token approval, or typed-data signature before an AI agent or wallet signs it.

Price / call$0.03

Seller volume →—

Success—

StatusUnknown

How this service works

Is this transaction, approval or signature safe to sign, explained for a person? The same pre-sign verdict as /v1/check (green/orange/red + reason codes) plus a short plain-language explanation in English or Dutch, for an agent to show its user before asking for approval. Bulk: 100 checks for $0.80 via /v1/credits.

Output

A structured response containing a risk verdict (green = safe, orange = caution, red = dangerous) and a plain-language explanation in the requested language (English or Dutch) describing what the action does and why it received that verdict. May include a risk grade and specific flags such as a newly registered origin domain or an out-of-mandate payment.

Example use cases

Explain approval risk in Dutch

“Check this ERC-20 approval on Ethereum mainnet (chainId 1) — the token contract is 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48, the spender is 0x1111111254EEB25477B68fb85Ed929f73A960582, the amount is 1000000000, and give me the explanation in Dutch so our user can understand it.”

Verify EIP-3009 payment mandate

“I'm about to execute an x402 payment. The typed data is {EIP-3009 payload}, chainId is 8453 (Base), and there's a mandate attached — can you run a presign risk check and explain in English whether this payment is within the mandate limits and safe to sign?”

Assess risky contract transaction

“Before my agent submits this transaction on Arbitrum (chainId 42161) to contract 0xabc123…, with calldata 0xd0e30db0 and a value of 500000000000000000 wei, give me a risk verdict and a plain-language explanation of what this contract call actually does and whether it looks malicious.”

Technical details

Endpoint

POSThttps://presign-guard.fizzl.eu/v1/check/explain?utm_source=zero.xyz

When to prefer

Choose this endpoint over the bare /check endpoint when you need a human-readable explanation alongside the verdict — especially for end-user-facing flows, multilingual (Dutch/English) wallets, or when an AI agent needs to relay the rationale to a user in plain language. Use /check/explain any time the user needs to understand *why* a transaction is risky, not just the verdict.

Side effects

Missing required fields for the chosen type (e.g. no 'to' for transaction) — returns validation error
Unsupported chainId — returns error indicating chain not supported
Malformed calldata or typedData — returns parse error
Insufficient credits or payment failure — returns 402 Payment Required
Origin domain age check unavailable — orange verdict may not fire for new domains
EIP-3009 mandate signature mismatch — returns red verdict with explanation

Input

Schema · Request body

Field	Type	Description
to	string	transaction: target contract
tx	object	xrpl: the unsigned transaction JSON
data	string	transaction: 0x-prefixed calldata
from	string	optional: your wallet; an EVM transaction is then simulated
lang	string	explain only: en or nl
type	string	What is about to be signed
x402	object	optional, EIP-3009 payments: the x402 accepts entry being paid
token	string	approval: token contract
value	string	transaction: native value in wei
amount	string	approval: amount in base units (0 = revoke)
intent	string	optional: what the agent means to do, in one sentence
method	string	message: personal_sign (default) or eth_sign
origin	string	optional: the site asking (URL or hostname)
chainId	integer	EVM chain; required for approval, transaction and signature
mandate	object	optional, EIP-3009 payments: the spending mandate paid under
message	string	message: the text or 0x-hex to be signed
network	string	xrpl: xrpl:0 (default) or xrpl:1
spender	string	approval: who gets the allowance
typedData	—	signature: the eth_signTypedData_v4 payload
transaction	string	solana: the base64 wire transaction; algorand: one base64 msgpack transaction
transactions	array	algorand: an atomic group, each base64 msgpack

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