# AgentTools EVM Transaction Explainer

> AgentTools EVM Transaction Explainer is a paid API for AI agents from agentstoolshub.com, paid per call via x402, $0.015/call, status unknown (last checked 2026-10-12).

Decodes EVM transaction calldata and simulates it against live chain state to explain what it would do — including unlimited-approval warnings — without broadcasting it.

## Facts

- Endpoint: GET https://agentstoolshub.com/api/v1/crypto/tx-explain?utm_source=zero.xyz
- Price: $0.015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agenttools-evm-transaction-explainer-b9b0cf17
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IqrSfCiQ8l01Iy6hoXBQX

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 agenttools-evm-transaction-explainer-b9b0cf17
```

Example prompt: Before I sign this transaction, can you decode and simulate the calldata 0xa9059cbb000000000000000000000000abcdef1234567890abcdef1234567890abcdef12000000000000000000000000000000000000000000000000de0b6b3a7640000 sent to 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on base, and tell me if there are any unlimited-approval risks?

## When to prefer this

Use this endpoint when an AI agent or wallet interface needs to explain an EVM transaction to a user before they sign it — especially for DeFi interactions, token approvals, or any calldata that may be opaque. Prefer this over generic ABI decoders when you also need live simulation (will it revert?) and security warnings (unlimited approvals). Ideal for agent-driven signing flows on Base or Ethereum where user safety and informed consent matter.

## Known failure modes

- Unknown calldata selector not found in 4byte directory — returns raw hex with partial decode
- Invalid 'to' address format — returns 400 error
- Simulation reverts on-chain — returns revert reason if available, or generic revert
- Unsupported chain value — returns validation error
- Malformed hex calldata — returns parse error
- Network timeout fetching live chain state — returns 503 or timeout error

## How this service works

Explain what an EVM transaction would actually do: decodes the calldata (ERC-20 transfers/approvals via known ABIs, unknown selectors via the 4byte directory) and simulates the call against live chain state to report the outcome — including unlimited-approval warnings — without sending anything. Use this when an agent needs to decode and simulate a transaction — before signing it.

## Output

Returns a human-readable explanation of the transaction: the decoded function name and parameters (e.g. 'transfer 100 USDC to 0xABC...'), a simulation result indicating whether the call would succeed or revert against current chain state, token amounts and recipients for ERC-20 transfers, and a prominent warning if the transaction grants an unlimited (max uint256) token approval.

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "to",
      "data"
     ],
     "properties": {
      "to": {
       "type": "string",
       "description": "To address"
      },
      "data": {
       "type": "string",
       "description": "Calldata (0x hex)"
      },
      "chain": {
       "enum": [
        "base",
        "ethereum"
       ],
       "type": "string",
       "description": "Chain"
      },
      "value": {
       "type": "string",
       "description": "Value (wei, optional)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agenttools-evm-transaction-explainer-b9b0cf17/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentstoolshub.com](https://www.zero.xyz/host/agentstoolshub.com/llms.txt)