# EVM Transaction Explainer

> EVM Transaction Explainer is a paid API for AI agents from evm-tx-toolkit.mtree.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

Fetches a confirmed EVM transaction by hash and returns a human-readable explanation including contracts invoked, method, token balance changes, approvals, gas used, and a one-line summary

## Facts

- Endpoint: POST https://evm-tx-toolkit.mtree.workers.dev/tools/tx_explainer
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-tx-toolkit-mtree-workers-dev-831f16f2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__xxXJQl7DOn9ZIp1F10E2

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 evm-tx-toolkit-mtree-workers-dev-831f16f2 -d '<json body>'
```

Example prompt: Can you explain what happened in this Ethereum transaction — 0x4a1b2c3d... — which chain it was on (Base), what contracts were called, what tokens moved, and give me a plain-English summary of what the trade did?

## When to prefer this

Use this endpoint when you need a human-readable, structured explanation of a confirmed on-chain EVM transaction — especially for post-trade analysis, audit trails, user-facing trade summaries, or understanding what a historical transaction actually did. Prefer this over raw RPC calls when you want pre-parsed token balance changes, approval detection, and a natural-language summary without writing your own decoder.

## Known failure modes

- Transaction hash not found or not yet confirmed — returns error indicating tx is pending or invalid
- Unsupported chain specified — returns error if chain is not Base, Ethereum, Arbitrum, Optimism, or Polygon
- Malformed transaction hash — returns validation error
- Payment not provided or insufficient — x402 payment required (0.10 USDC on Base) or returns 402 error
- RPC timeout or node unavailability — returns upstream error

## How this service works

EVM transaction explainer for Base, Ethereum, Arbitrum, Optimism, and Polygon. Fetch a confirmed transaction by hash and return a human-readable pre-action/post-trade explanation: programs/contracts invoked, method, token balance changes, approvals, fee/gas used, transfer list, and one-line summary. Returns JSON. Price 0.10 USDC on Base via x402. Demo/preview: https://evm-tx-toolkit.mtree.workers.dev/demo/tx/explain. Contact: https://evm-tx-toolkit.mtree.workers.dev/contact.

## Output

A JSON object containing: contracts/programs invoked, the method called, token balance changes before and after the transaction, any ERC-20 approvals granted, gas/fee used, a full transfer list, and a concise one-line human-readable summary of what the transaction did.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "chain",
      "tx_hash"
     ],
     "properties": {
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "arbitrum",
        "optimism",
        "polygon"
       ],
       "type": "string",
       "example": "base",
       "description": "EVM chain slug"
      },
      "tx_hash": {
       "type": "string",
       "example": "0x0000000000000000000000000000000000000000000000000000000000000000",
       "pattern": "^0x[0-9a-fA-F]{64}$",
       "description": "0x-prefixed transaction hash"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "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/evm-tx-toolkit-mtree-workers-dev-831f16f2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from evm-tx-toolkit.mtree.workers.dev](https://www.zero.xyz/host/evm-tx-toolkit.mtree.workers.dev/llms.txt)