# Legible Check – x402 Preflight Inspector

> Legible Check – x402 Preflight Inspector is a paid API for AI agents from legible-check.ezealfa.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).

Inspects an x402-protected endpoint's 402 response envelope and checks its CDP and PayAI discovery status without making any payment.

## Facts

- Endpoint: GET https://legible-check.ezealfa.workers.dev/x402check?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/legible-check-x402-preflight-inspector-8b695625
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_N8bv3WQtQwbaOND8AB8Xy

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 legible-check-x402-preflight-inspector-8b695625
```

Example prompt: Can you preflight check this x402 endpoint — https://example.com/paid-api — using a GET request, and tell me what the 402 envelope looks like and whether it's discoverable on PayAI and CDP, without actually paying anything?

## When to prefer this

Use this endpoint when you need to inspect an x402 payment envelope and check discovery status before committing to a payment, or when debugging whether an x402 endpoint is correctly configured and discoverable. Prefer this over directly calling the target when you want a zero-cost, read-only preflight that aggregates 402 envelope data plus CDP and PayAI registration status in one call.

## Known failure modes

- Target URL is not a valid x402 endpoint and returns a non-402 response
- Target endpoint is unreachable or times out
- URL is not HTTPS or is malformed
- HTTP method provided is not in the allowed set (GET, HEAD, DELETE)
- PayAI or CDP discovery lookup fails independently of the target endpoint

## How this service works

x402 endpoint preflight: inspect the 402 envelope and check CDP and PayAI discovery status; no payment is made to the target.

## Output

Returns the parsed contents of the target endpoint's 402 response envelope (payment metadata, accepted tokens, pricing) along with the endpoint's discovery status on both Coinbase CDP and PayAI, without making any actual payment to the target.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "Public HTTPS x402 endpoint to pre-flight."
      }
     },
     "additionalProperties": false
    }
   },
   "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/legible-check-x402-preflight-inspector-8b695625/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from legible-check.ezealfa.workers.dev](https://www.zero.xyz/host/legible-check.ezealfa.workers.dev/llms.txt)