# SignalHarness URL Discovery Audit

> SignalHarness URL Discovery Audit is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Audits a given HTTPS URL for agent-discoverability and API accessibility, returning per-check pass/warn/fail results and discovered resource URLs

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/url_discovery_audit/invoke
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-url-discovery-audit-af9132e0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_PFe3UJvyuMl7lLzEWyCYp

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-url-discovery-audit-af9132e0 -d '<json body>'
```

Example prompt: Can you run a discovery audit on https://api.myservice.com and tell me which checks pass or fail, and what resource URLs it finds?

## When to prefer this

Choose this endpoint when you need a structured, per-check audit of whether a specific HTTPS URL is properly discoverable and accessible to AI agents — including a breakdown of what passes, warns, or fails and a list of resource URLs found. Prefer this over generic HTTP probers or link crawlers when you specifically care about agent-native discoverability criteria and want a machine-readable pass/warn/fail report with provenance receipt.

## Known failure modes

- URL does not start with https:// — rejected by input schema pattern validation
- URL exceeds 2048 characters — rejected by maxLength constraint
- Target URL is unreachable or returns non-200 — audit may complete with all-fail checks
- Malformed or non-URL string supplied — schema validation error
- Payment not fulfilled — 402 response before execution begins
- Service timeout if target URL is very slow to respond

## 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 audited URL, an array of individual checks each with an id, url, detail, and pass/warn/fail status, a summary count of passes/warns/fails, and an array of discovered resource URLs. Also includes a receipt with payment details, latency, execution metadata, and a result SHA256 hash.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "pattern": "^https://",
   "maxLength": 2048,
   "minLength": 9
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "url": "https://example.com/resource",
   "checks": [
    {
     "id": "example",
     "url": "https://example.com/resource",
     "detail": "example",
     "status": "pass"
    }
   ],
   "summary": {
    "fail": 0,
    "pass": 0,
    "warn": 0
   },
   "discoveredResourceUrls": [
    "example00"
   ]
  },
  "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": "url_discovery_audit",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "20000",
   "resultSha256": "a95dcf32d5fe7ca2029652a9cc7474e7d464af51b34b67987acbbc2f772defd4",
   "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-url-discovery-audit-af9132e0/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)