# x402 Trust Semantic Search

> x402 Trust Semantic Search is a paid API for AI agents from x402.fuchss.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-13).

Search the x402 endpoint catalog by natural language query and receive ranked matches with trust grades and similarity scores

## Facts

- Endpoint: POST https://x402.fuchss.app/v1/semantic-search?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-semantic-search-2a0f68e3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ilLNkfsAuzQweNxSgp93Y

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-trust-semantic-search-2a0f68e3 -d '<json body>'
```

Example prompt: Search the x402 Trust catalog for endpoints related to 'real-time stock price data' and return the top 5 matches with their trust grades and similarity scores.

## When to prefer this

Use this endpoint when you need to discover x402-compatible API endpoints by topic or capability description rather than by exact URL, especially when you want results pre-filtered by trust quality. Prefer this over a generic web search when you specifically want endpoints compatible with the x402 payment protocol and want cosine-similarity ranking combined with trust grades to surface reliable options quickly.

## Known failure modes

- Empty query string returns no matches or an error
- Limit set to 0 or a negative integer may cause a bad request response
- Query too long or malformed JSON body returns 400
- No matching endpoints in catalog returns count:0 with empty matches array
- Payment failure (insufficient USDC) blocks the request before processing
- Endpoints with null grade/score indicate not yet evaluated by the trust system

## How this service works

Trust, reputation & reliability scores for x402 endpoints. We monitor every listed x402 service 24/7: uptime probes, 402-envelope compliance, price history, and real on-chain USDC settlement volume. Free grade & recommendation for any endpoint, $0.005 for a full data breakdown.

## Output

A JSON object containing a ranked list of up to `limit` x402 endpoint matches, each with: endpoint ID, resource URL, trust grade (A–F or null if unscored), numeric trust score (0–100 or null), cosine similarity to the query, a short description, and a link to the full endpoint page on x402.fuchss.app. Results are sorted by cosine similarity with trust score as tiebreaker. Also includes total match count, the original query, and a timestamp.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limit": {
   "type": "integer"
  },
  "query": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "note": "Ranked by cosine similarity, with trust score as a tiebreaker. score/grade are null when the endpoint is not yet scored. No verdict or flag detail here: POST /v1/x402-trust carries those.",
  "count": 2,
  "query": "weather forecast",
  "matches": [
   {
    "id": 12345,
    "grade": "A",
    "score": 88.1,
    "resource": "https://api.weather.example/v1/forecast",
    "similarity": 0.912,
    "description": "Hyperlocal weather forecasts, priced per call.",
    "endpointPage": "https://x402.fuchss.app/endpoint/12345"
   },
   {
    "id": 12399,
    "grade": null,
    "score": null,
    "resource": "https://wx.example.net/api/now",
    "similarity": 0.874,
    "description": null,
    "endpointPage": "https://x402.fuchss.app/endpoint/12399"
   }
  ],
  "generatedAt": 1782826208450
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-trust-semantic-search-2a0f68e3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.fuchss.app](https://www.zero.xyz/host/x402.fuchss.app/llms.txt)