# RAG Retrieval Precision@K Evaluation

> RAG Retrieval Precision@K Evaluation 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).

Computes Precision@K metric for a RAG retrieval system, measuring how many of the top-K retrieved documents are actually relevant.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/rag_retrieval_precision_at_k/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/rag-retrieval-precision-k-evaluation-8ca92db5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CmWmFKU4yn92sNJs-UVuW

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 rag-retrieval-precision-k-evaluation-8ca92db5 -d '<json body>'
```

Example prompt: Evaluate my RAG retrieval system's Precision@5 — I retrieved these 5 documents and the relevant ones are documents 1, 3, and 5; tell me my precision score and any warnings.

## When to prefer this

Choose this endpoint when you need a quick, pay-per-call Precision@K computation for RAG or information retrieval evaluation without standing up your own evaluation infrastructure. Ideal for one-off benchmarks, CI/CD quality gates, or comparing retrieval configurations in an agent-native workflow using Base USDC micropayments.

## Known failure modes

- Malformed or empty request_json input returns an error or invalid result
- K value larger than the retrieved set size may produce undefined or trivially low scores
- Caller-supplied relevance labels that are inconsistent or incorrect lead to unreliable precision scores
- Missing required fields in request_json may cause computation 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 analysis containing the Precision@K score, a service ID, a scope note indicating the result is based on caller-supplied data, and warnings to verify the data before relying on results. Also includes a receipt with payment details, execution metadata, and a SHA256 hash of the result for auditability.

## 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": "rag_retrieval_precision_at_k",
   "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": "rag_retrieval_precision_at_k",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "ef726ce1c7b4ce45873673f7a6f2573c5e19be21ad46410ec3c4f870b421d600",
   "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/rag-retrieval-precision-k-evaluation-8ca92db5/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)