# SignalHarness ABI Encoding Diagnostician

> SignalHarness ABI Encoding Diagnostician 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).

Analyzes and diagnoses ABI (Application Binary Interface) encoding issues in smart contract data, returning structured warnings and diagnostic findings.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/abi_encoding_diagnose/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-encoding-diagnostician-f5e7870f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BRGA_iGp3gJuO5QYIz9oT

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-encoding-diagnostician-f5e7870f -d '<json body>'
```

Example prompt: Can you diagnose the ABI encoding issues in this calldata: '0x23b872dd000000000000000000000000...'? I think there's a parameter mismatch with a transferFrom call.

## When to prefer this

Choose this endpoint when you need to diagnose or debug ABI encoding problems in EVM smart contract calldata, particularly when a transaction is reverting or a contract call is behaving unexpectedly due to parameter encoding issues. It is especially useful for AI agents that auto-generate contract calls and need to self-verify encoded payloads before submission. Prefer this over general-purpose code analyzers when you specifically need ABI-aware diagnostics with structured warnings and evidence scope.

## Known failure modes

- Input string too short (below 2 characters) or too long (above 65536 characters) returns validation error
- Malformed or unparseable ABI data may yield empty diagnostics with no warnings
- Payment failure on x402 protocol results in 402 response before execution
- Network or service timeout returns error status in receipt
- Non-ABI-formatted string may produce low-confidence or generic diagnostic output

## 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 an ABI encoding diagnostic string describing the issues found, a list of warnings, the evidence scope (indicating the data was caller-supplied), and the service ID. Also includes a full receipt with payment details, execution metadata, network info, and a result SHA-256 hash for verification.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Diagnostics do not simulate execution or prove contract behavior."
   ],
   "service_id": "abi_encoding_diagnose",
   "evidence_scope": "caller_supplied_data",
   "abi_encoding_diagnostic": "{\"byte_length\":36,\"decode_valid\":true,\"decoded\":{\"args\":[\"0x0000000000000000000000000000000000000001\"],\"functionName\":\"balanceOf\"},\"has_selector\":true,\"payload_word_aligned\":true,\"selector\":\"0x70a08231\",\"valid_hex\":true}"
  },
  "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_encoding_diagnose",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "4127435eb6889e1d69936bef322d036863abc83b88c31cabbf116e983594c4e4",
   "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-encoding-diagnostician-f5e7870f/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)