# AMNT Transaction Preflight

> AMNT Transaction Preflight is a paid API for AI agents from www.amnt.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Simulates an EVM transaction before signing and returns a safety verdict (safe/warn/danger) to help users avoid risky or malicious transactions.

## Facts

- Endpoint: POST https://www.amnt.io/api/os-tools/tx-preflight
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/amnt-transaction-preflight-a9b7f6b4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FZhUC1heBLJzHKdkMEOKq

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability amnt-transaction-preflight-a9b7f6b4 -d '<json body>'
```

Example prompt: Before I sign this transaction, simulate it and tell me if it's safe — it's going to 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base (chain 8453), from my wallet 0xYourWallet, with calldata 0x095ea7b3... and 0 wei value.

## When to prefer this

Use this endpoint when an AI agent or user needs to assess the risk of an EVM transaction before signing — especially for approvals, DeFi interactions, or any calldata received from an untrusted source. Ideal for wallet UX flows, agent-driven DeFi automation, or phishing protection pipelines. Prefer this over static calldata decoders when you need a simulation-backed verdict rather than just ABI decoding.

## Known failure modes

- Invalid or malformed hex calldata returns an error
- Unsupported chain ID (only 1, 10, 137, 8453, 42161 are supported)
- Simulation may fail if the 'from' address has insufficient balance for the simulation
- Contract not deployed at 'to' address causes simulation failure
- Malformed Ethereum address format returns validation error

## How this service works

Tx Preflight - Simulate a transaction before you sign it and get a safe / warn / danger verdict.

## Output

Returns a safety verdict of safe, warn, or danger for the simulated transaction, along with contextual details about what the transaction would do — such as allowance changes, token transfers, or suspicious patterns detected during simulation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string",
   "examples": [
    "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
   ],
   "maxLength": 42,
   "description": "The contract or wallet this transaction is aimed at."
  },
  "data": {
   "type": "string",
   "examples": [
    "0x095ea7b3..."
   ],
   "maxLength": 20000,
   "description": "The transaction's data field, hex. Omit for a plain native-token send."
  },
  "from": {
   "type": "string",
   "examples": [
    "0xYourWallet..."
   ],
   "maxLength": 42,
   "description": "The wallet that would sign. Used for the simulation and the allowance read."
  },
  "value": {
   "type": "string",
   "default": "0",
   "examples": [
    "0"
   ],
   "maxLength": 32,
   "description": "Native token sent with the call, in wei. Decimal string."
  },
  "chainId": {
   "enum": [
    "8453",
    "1",
    "10",
    "42161",
    "137"
   ],
   "type": "string",
   "default": "8453",
   "description": "Which chain to simulate against."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/amnt-transaction-preflight-a9b7f6b4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from www.amnt.io](https://www.zero.xyz/host/www.amnt.io/llms.txt)