# SignalHarness ABI Constructor Encode

> SignalHarness ABI Constructor Encode 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).

ABI-encodes constructor arguments for Ethereum smart contract deployment bytecode

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/abi_constructor_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-constructor-encode-a62ddf95
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4urrSCZqeIjVVw8pYFZ90

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-constructor-encode-a62ddf95 -d '<json body>'
```

Example prompt: ABI-encode the constructor arguments for my ERC20 token contract — the constructor takes a string name 'MyToken', a string symbol 'MTK', and a uint256 initial supply of 1000000000000000000000000, and I need the encoded deployment data to append to my bytecode.

## When to prefer this

Choose this endpoint when you need a hosted, pay-per-call service to ABI-encode Ethereum smart contract constructor arguments without setting up a local ethers.js or viem environment. Particularly useful for AI agents orchestrating contract deployments that lack a local EVM library, or when you need a reliable, receipted, auditable encoding step with a SHA-256 result hash for verification. At $0.01 USDC per call it is cost-effective for single deployments or low-frequency pipelines.

## Known failure modes

- Invalid ABI constructor request JSON causes a parsing error
- Mismatched parameter types and values result in encoding failure or warnings
- Malformed ABI type strings (e.g. unrecognized Solidity types) cause rejection
- Request exceeds 65536 character limit returns validation error
- Payment failure via x402 protocol results in no execution
- Network or service unavailability returns a failed status in the receipt

## 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 ABI-encoded constructor calldata as a hex string in 'encoded_deployment_data', any warnings about the encoding process, the service_id, evidence_scope, and a full payment receipt with request/execution IDs, network (Base/eip155:8453), amount paid, latency, and a SHA-256 hash of the result for verification.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Output is unsigned data and is never broadcast."
   ],
   "service_id": "abi_constructor_encode",
   "evidence_scope": "caller_supplied_data",
   "encoded_deployment_data": "{\"data\":\"0x000000000000000000000000000000000000000000000000000000000000000001\"}"
  },
  "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_constructor_encode",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "f13d5dc36871283c02d72af2313985dc961c981d9e12218d6a579e7cf37141e1",
   "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-constructor-encode-a62ddf95/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)