# x402 Listing Quality Scanner

> x402 Listing Quality Scanner is a paid API for AI agents from x402-niche-briefs.fly.dev, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Returns a quality snapshot of x402 API listings from public discovery catalogs, scoring unique-payer activity versus wash trading when quality fields are available.

## Facts

- Endpoint: GET https://x402-niche-briefs.fly.dev/v1/listing-quality
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-listing-quality-scanner-f92232e8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_T--fT5POa1RUA8fis00pM

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 x402-listing-quality-scanner-f92232e8
```

Example prompt: Can you pull a listing quality snapshot from the x402 discovery catalogs and tell me how many listings have real unique payers versus suspected wash activity?

## When to prefer this

Choose this endpoint when you need an objective, data-driven quality assessment of x402 API listings from public discovery catalogs, particularly to distinguish genuine marketplace activity from wash trading. It is best suited for vetting listings before integration, auditing marketplace integrity, or monitoring catalog health. Prefer this over manual inspection or generic API directory browsing when you need scored, structured quality signals with transparency about data provenance.

## Known failure modes

- Cache miss may cause slightly higher latency on first call within 15-minute window
- Quality fields absent for some listings — scoring may be incomplete or omitted
- Discovery catalog unavailable — endpoint may return empty or partial results
- Invalid request method returns error (only GET supported)
- Upstream CDP or PayAI catalog unreachable — degraded or no data returned

## How this service works

x402 listing-quality snapshot from public discovery catalogs (CDP and/or PayAI). Scores unique-payer vs wash when quality fields exist. No invented market sizes. Cached 15 minutes.

## Output

Returns a cached (15-minute TTL) quality snapshot of x402 API listings sourced from public discovery catalogs (CDP and/or PayAI), including scores distinguishing unique payers from wash activity when quality fields are present. No synthetic or invented market size figures are included.

## 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",
     "properties": {}
    }
   },
   "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/x402-listing-quality-scanner-f92232e8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-niche-briefs.fly.dev](https://www.zero.xyz/host/x402-niche-briefs.fly.dev/llms.txt)