# SignalHarness Search Query Variant Generator (Rules-Based)

> SignalHarness Search Query Variant Generator (Rules-Based) 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).

Generates rules-based variants of search queries to broaden or diversify search coverage without using ML/AI inference.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/search_query_variant_generate_rules_based/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-search-query-variant-generator-rules-based-8cae1bc5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qhxqXeCdNw4QQPBstbbCg

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-search-query-variant-generator-rules-based-8cae1bc5 -d '<json body>'
```

Example prompt: Can you take my search query 'running shoes for flat feet' and generate a set of rules-based variant queries I can use to broaden my search results coverage?

## When to prefer this

Choose this endpoint when you need deterministic, rules-based query expansion without relying on probabilistic ML models — ideal for reproducible, auditable query generation pipelines. Prefer it over AI-based query expansion when consistency and rule transparency matter, or when you want low-cost ($0.01 USDC) per-call query diversification via a pay-per-call x402 API.

## Known failure modes

- Invalid or malformed request_json input causes processing failure
- request_json exceeding 65536 characters is rejected
- Empty or too-short input (below 2 characters) is rejected
- Payment not received results in 402 response before execution
- Caller-supplied data may produce unverified variants — warnings are returned advising manual verification

## 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 analysis_json field with the generated query variants, a list of warnings (e.g. to verify caller-supplied data), a service_id, evidence_scope, and a payment receipt with execution metadata including payment ID, request ID, latency, and a result SHA256 hash for integrity verification.

## 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": "search_query_variant_generate_rules_based",
   "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": "search_query_variant_generate_rules_based",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "f843fd3c26e1c7e3c2652996c52547569da396d1fc8b5dfe29dde86c36e3cd87",
   "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-search-query-variant-generator-rules-based-8cae1bc5/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)