# SignalHarness ABI Event Topics Decoder

> SignalHarness ABI Event Topics Decoder is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-16).

Decodes ABI-encoded Ethereum event topics from smart contract logs into human-readable structured data

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/abi_event_topics/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-abi-event-topics-decoder-d413dadf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AFCD5sVjJ0Y5Dnw5UoxwK

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 signalharness-abi-event-topics-decoder-d413dadf -d '<json body>'
```

Example prompt: Decode these ABI-encoded event topics from a smart contract log for me: [0xddf252ad1be2c89b69c2b068fc378daa952ba7f20b8ebc2e67d1a3d6f4a6b3a5, 0x000000000000000000000000abc123..., 0x000000000000000000000000def456...] — I need to know what event this is and what values were emitted.

## When to prefer this

Choose this endpoint when you need to decode raw ABI-encoded Ethereum event topics from smart contract transaction logs into structured, human-readable data. It is purpose-built for EVM log decoding, operates per-call at $0.01 USDC via x402, and returns an auditable receipt with a result hash — making it suitable for agent pipelines that require verifiable blockchain data extraction.

## Known failure modes

- Malformed or truncated ABI topic string returns a warning or failed status
- Input that is not valid ABI-encoded data may produce incorrect or empty decoded output
- Exceeding the 65536-character input limit causes a validation error
- Unsupported or unrecognized ABI event signatures may result in partial decoding with warnings

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a JSON object containing decoded event topics as human-readable data, any warnings about the input data, the service ID, and an evidence scope indicator. Also includes a full execution receipt with payment details, latency, a SHA-256 result hash, and settlement reference for auditability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "abi_event_topics_request": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Constructed topics do not query any chain."
   ],
   "service_id": "abi_event_topics",
   "event_topics": "{\"signature\":\"Changed(address,uint256)\",\"topics\":[\"0xb52dda022b6c1a1f40905a85f257f689aa5d69d850e49cf939d688fbe5af5946\",\"0x0000000000000000000000000000000000000000000000000000000000000001\"]}",
   "evidence_scope": "caller_supplied_data"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "abi_event_topics",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "6858fbc2bffcb1165931364d11fdbcfc05e8571ab284c6513dcb18cce06b38f3",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-abi-event-topics-decoder-d413dadf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)