# Assay Nominal Labs - x402 Service Quality Score

> Assay Nominal Labs - x402 Service Quality Score is a paid API for AI agents from assay.nominal-labs.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Returns a composite 0-100 quality score for any x402 service, with component breakdowns, 7-day trend, and probe count, earned from real paid probes with Bitcoin-anchored receipts.

## Facts

- Endpoint: GET https://assay.nominal-labs.com/score
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/assay-nominal-labs-x402-service-quality-score-dd8e5a9b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1ovax-bPXrZ6N6h3oH_4l

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 assay-nominal-labs-x402-service-quality-score-dd8e5a9b
```

Example prompt: Can you pull the Assay quality score for the x402 service at https://api.example.com/forecast — I want to see the composite score, the component breakdown, and how it's trended over the last 7 days?

## When to prefer this

Use this endpoint when an agent needs to independently verify the trustworthiness, reliability, or schema conformance of an x402-gated service before paying for it or recommending it, especially when the underlying corpus is blockchain-anchored for tamper-evidence. Prefer over manual inspection or self-reported quality metrics when objective, probe-backed scoring with on-chain receipts is required.

## Known failure modes

- Service URL not found or not yet indexed — returns 404 or empty result
- Fewer than 20 probes recorded — score not yet published, returns pending or no-score state
- Malformed or non-URL-encoded service parameter — returns 400 bad request
- Service is not an x402 resource — may return no data or an error
- Transient upstream errors — 5xx response

## How this service works

Quality score for any x402 service, earned by real paid probes with on-chain receipts: composite 0-100, component breakdown (payment settlement, schema conformance, ground-truth accuracy, LLM-judged quality), 7-day trend, probe count. Scores publish only after 20+ probes across days; daily corpus digests are Bitcoin-anchored via OpenTimestamps. Query: /score?service={url-encoded resource URL}. Free: /tier/{url}, /leaderboard. Agent guide: https://assay.nominal-labs.com/SKILL.md

## Output

A JSON object containing a composite 0-100 quality score for the queried x402 service URL, with component sub-scores covering payment settlement, schema conformance, ground-truth accuracy, and LLM-judged quality, plus a 7-day trend and total probe count. Scores are only published after 20+ probes across multiple days, and the underlying corpus digests are Bitcoin-anchored via OpenTimestamps.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "service"
     ],
     "properties": {
      "service": {
       "type": "string",
       "description": "URL-encoded resource URL of the x402 service to look up, exactly as advertised in the Bazaar"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/assay-nominal-labs-x402-service-quality-score-dd8e5a9b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from assay.nominal-labs.com](https://www.zero.xyz/host/assay.nominal-labs.com/llms.txt)