# TxSim Safe-to-Sign Checker

> TxSim Safe-to-Sign Checker is a paid API for AI agents from simulate.cyberwarex.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Returns a single pre-sign safety verdict (GREEN, REVIEW, or BLOCK) by fusing transaction simulation, address risk screening, URL phishing detection, and token safety checks for EVM wallet agents.

## Facts

- Endpoint: GET https://simulate.cyberwarex.com/safe-to-sign
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/txsim-safe-to-sign-checker-2e18901e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_49MKzZTHSDjCTtbzVtpNM

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 txsim-safe-to-sign-checker-2e18901e
```

Example prompt: Before my wallet signs this transaction — sending 0.5 ETH to 0xAbc123... on Ethereum with calldata 0xdeadbeef... — can you run a safety check and tell me if it's GREEN, REVIEW, or BLOCK?

## When to prefer this

Use this endpoint when an AI wallet agent needs a single fused pre-sign safety decision rather than calling separate services for transaction simulation, address screening, URL phishing, and token checks individually. It is best suited for real-time, per-transaction gating in agentic DeFi or wallet automation pipelines where a fast go/no-go verdict is required before user signature.

## Known failure modes

- Invalid or malformed 'to' address returns an error or inconclusive verdict
- Unsupported chain identifier causes a validation error
- Malformed calldata hex (non-0x prefix or odd length) results in decode failure
- Missing required 'to' field may return an incomplete analysis
- Unknown or very new contract addresses may yield insufficient data for a confident verdict
- Network timeouts during simulation return a fallback REVIEW verdict

## How this service works

One pre-sign safety verdict (GREEN, REVIEW or BLOCK) fusing transaction, signature, address, URL and token checks for AI wallet agents.

## Output

A single verdict label (GREEN, REVIEW, or BLOCK) along with supporting risk signals covering the transaction simulation outcome, address risk screening result, URL phishing assessment, and token safety flags — giving an AI wallet agent a fused go/no-go decision before a user signs.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "to": {
       "type": "string",
       "description": "Transaction target address (0x...)."
      },
      "url": {
       "type": "string",
       "description": "A URL to phishing-check (optional)."
      },
      "data": {
       "type": "string",
       "description": "Transaction calldata hex (0x...)."
      },
      "from": {
       "type": "string",
       "description": "Sender address for the eth_call preview (optional)."
      },
      "chain": {
       "type": "string",
       "description": "EVM chain for tx/token checks (base, bsc, ethereum, polygon, arbitrum, optimism). Default base."
      },
      "token": {
       "type": "string",
       "description": "A token address to safety-check (optional; inferred from 'to' when it is a token)."
      },
      "value": {
       "type": "string",
       "description": "Native value (wei, decimal or hex). Default 0."
      },
      "address": {
       "type": "string",
       "description": "A counterparty address to risk-screen (optional; 'to' is screened automatically)."
      },
      "message": {
       "type": "string",
       "description": "personal_sign message to check (instead of typed_data)."
      },
      "typed_data": {
       "type": "string",
       "description": "EIP-712 typed data JSON string to check as a signature request."
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/txsim-safe-to-sign-checker-2e18901e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from simulate.cyberwarex.com](https://www.zero.xyz/host/simulate.cyberwarex.com/llms.txt)