# x402 Doctor — URL Payability Checker

> x402 Doctor — URL Payability Checker is a paid API for AI agents from agentx.sale, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-21).

Validates whether a URL is a properly implemented x402 agent-payable resource, grading it against v1 and v2 of the x402 spec and returning a verdict with grade

## Facts

- Endpoint: GET https://agentx.sale/x402/x402-check?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-doctor-url-payability-checker-df761ba0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A2Q4zlMfJmNBdMZas0CUG

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-doctor-url-payability-checker-df761ba0
```

Example prompt: Check if https://example.com/paid-resource is a valid x402 agent-payable endpoint — run both the v1 and v2 spec checks and give me a compliance grade and verdict.

## When to prefer this

Use this endpoint when you need to verify that a specific URL correctly implements the x402 payment protocol before integrating it into an agentic workflow, or when debugging why an x402-protected resource is not behaving as expected. Prefer this over manual spec review when you need a quick, graded, machine-readable compliance verdict covering both v1 and v2 of the x402 spec.

## Known failure modes

- Target URL is unreachable or returns a non-402 status when probed — validation cannot proceed
- URL is not an HTTP GET endpoint — method mismatch with x402 check requirements
- Target URL has no x402 payment headers at all — returns not-a-paid-resource verdict
- Network timeout reaching the target URL
- Malformed URL input causes schema validation error

## How this service works

x402 Doctor: is a URL a valid agent-payable paid resource? v1+v2 spec check with grade and verdict

## Output

Returns a compliance verdict and grade indicating whether the target URL correctly implements the x402 paid resource protocol, with specific feedback against v1 and/or v2 spec requirements, highlighting any failures or gaps in the implementation.

## 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": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://example.com/paid",
  "grade": "A",
  "verdict": "agent-payable"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-doctor-url-payability-checker-df761ba0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentx.sale](https://www.zero.xyz/host/agentx.sale/llms.txt)