# SignalHarness Agent Tool Call Argument Checker

> SignalHarness Agent Tool Call Argument Checker is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Validates and analyzes JSON arguments passed to agent tool calls, returning warnings and analysis about the caller-supplied data.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/agent_tool_call_argument_check/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-agent-tool-call-argument-checker-92dda7de
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JzoDRq55U8suX7V7h9D5V

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-agent-tool-call-argument-checker-92dda7de -d '<json body>'
```

Example prompt: Can you check these JSON arguments I'm about to pass to an agent tool call and tell me if there are any issues or warnings? Here's the payload: {"city": "New York", "date": "2025-06-01", "count": 5}

## When to prefer this

Use this endpoint when an AI agent needs to validate or sanity-check JSON arguments before passing them to a tool call, especially in safety-critical or payment-adjacent workflows. It is particularly valuable when agents generate their own arguments and you want a second-pass check for malformed data, suspicious values, or schema violations. Prefer this over rolling your own JSON schema validator when you want a pay-per-call, agent-native service with a receipt and audit trail.

## Known failure modes

- Malformed or non-JSON request_json string returns an error
- Payload exceeds 65536 character limit and is rejected
- Caller-supplied data may not represent true schema validity — warnings always note to verify independently
- Payment failure via x402 prevents execution
- Ambiguous or missing request_json field causes invocation failure

## 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 indicating whether the call is a replay, the service ID, an analysis_json string containing the parsed and validated argument data, an evidence_scope field indicating the data source (e.g. 'caller_supplied_data'), a list of warnings, and a full receipt object with payment details, latency, execution IDs, and a SHA-256 result hash.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Verify the caller-supplied data before relying on this result."
   ],
   "service_id": "agent_tool_call_argument_check",
   "analysis_json": "{\"example\":\"schema-valid caller-supplied data\"}",
   "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": "agent_tool_call_argument_check",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "381c26a429b5fdd738a82a32af7e0086e023d001d00e86a8c87828bda3c75acb",
   "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-agent-tool-call-argument-checker-92dda7de/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)