# Base Transaction Explainer

> Base Transaction Explainer is a paid API for AI agents from agent-utils-x402.fishbowlinc.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-11-02).

Decodes and explains any Base mainnet transaction in plain English plus structured JSON, including status, fees, token transfers, approvals, swaps, and net balance changes

## Facts

- Endpoint: GET https://agent-utils-x402.fishbowlinc.workers.dev/v1/base-tx?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-transaction-explainer-282c9145
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-G3r6pWPYqa_CzVvdamiY

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 base-transaction-explainer-282c9145
```

Example prompt: Can you explain what happened in this Base transaction — 0x3a7f2c1d9e4b8f05c6a2d3e7f1b9c4d5a8e2f6b3c7d1a4e9f2b5c8d3e6a1f4b7 — in plain English, including any token transfers, fees, and whether there were any unlimited approvals?

## When to prefer this

Use this endpoint when you need a human-readable breakdown of a Base mainnet transaction with structured decoded data — including fees, token transfers, approvals, and net balance changes — without running your own RPC node or writing ABI decoding logic. Prefer it over raw RPC calls when the goal is to explain or audit a transaction to a user rather than query chain state programmatically.

## Known failure modes

- Invalid tx hash format (must be 0x + 64 hex chars) returns 400 error
- Transaction not found on Base mainnet returns 404
- Non-Base (e.g. Ethereum mainnet or other L2) tx hashes return no results or error
- Payment not included or insufficient USDC ($0.005 required via x402) returns 402
- Rate limiting or Cloudflare Worker timeout on complex transactions

## How this service works

Explain any Base mainnet transaction in plain English plus structured JSON: status, method name, fee (L2+L1), decoded ERC-20/NFT transfers with token symbols and decimals, approvals (flags unlimited), swaps, wraps, EIP-3009 relays, and the sender's net token changes. Query: hash (0x + 64 hex).

## Output

Returns a plain-English summary of what the transaction did plus structured JSON containing: success/fail status, the contract method name called, L1 and L2 gas fees, a list of decoded ERC-20 and NFT transfers with token symbols and decimals, token approvals with unlimited-flag detection, swap events, wrap/unwrap events, EIP-3009 relay metadata, and the sending address's net token balance changes across all involved assets.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "hash"
     ],
     "properties": {
      "hash": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{64}$"
      }
     }
    }
   },
   "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/base-transaction-explainer-282c9145/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-utils-x402.fishbowlinc.workers.dev](https://www.zero.xyz/host/agent-utils-x402.fishbowlinc.workers.dev/llms.txt)