# SignalHarness ABI Function Encoder

> SignalHarness ABI Function Encoder is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Encodes an Ethereum ABI function call into its hex-encoded calldata representation, ready for on-chain transaction submission.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/abi_function_encode/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-abi-function-encoder-c5974f41
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7nM8Vw6c4AEh2kAmLjhPz

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-function-encoder-c5974f41 -d '<json body>'
```

Example prompt: Encode an ABI function call for the ERC-20 transfer function — the function signature is 'transfer(address,uint256)', the recipient address is 0xAbCd...1234, and the amount is 1000000000000000000 (1 ETH in wei).

## When to prefer this

Choose this endpoint when you need a reliable, pay-per-use ABI encoding service accessible via HTTP without running local Web3 tooling (ethers.js, web3.py, viem, etc.). Ideal for AI agents, serverless pipelines, or lightweight environments that need to construct Ethereum transaction calldata on the fly without installing blockchain SDKs. At $0.01 USDC per call via x402, it is cost-effective for low-to-medium volume encoding tasks.

## Known failure modes

- Invalid or malformed ABI function definition string — returns an error status with a description of the parse failure
- Parameter type mismatch (e.g. supplying a string where an address is expected) — may return encoding errors or warnings
- Input exceeds maximum length of 65536 characters — rejected with a validation error
- Missing required 'abi_function_encode_request' field — request rejected
- Network or payment failure prevents execution — status set to failed with no encoded 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 the hex-encoded ABI function calldata in the 'encoded_function_data' field, along with any encoding warnings, the service ID ('abi_function_encode'), evidence scope, a signed receipt with payment details (paymentId, receiptId, requestId, executionId, network, amount, resultSha256), and the overall execution status.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Encoding does not simulate execution or prove contract compatibility."
   ],
   "service_id": "abi_function_encode",
   "evidence_scope": "caller_supplied_data",
   "encoded_function_data": "{\"data\":\"0x70a082310000000000000000000000000000000000000000000000000000000000000001\",\"signature\":\"balanceOf(address)\"}"
  },
  "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_function_encode",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "b343fb3b0eb1d9351456207655f12dfa4440e28ddf662cc09cd1fe94de7fa2d0",
   "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-function-encoder-c5974f41/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)