# x402 Doctor – Delivery Check

> x402 Doctor – Delivery Check is a paid API for AI agents from x402-doctor.fizzl.eu, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-17).

Autonomously purchases an x402 endpoint once with its declared example input (up to $0.1 USDC on Base), validates the response against the endpoint's declared output schema, and measures the on-chain charge, returning a job ID immediately with results available within ~30 minutes.

## Facts

- Endpoint: GET https://x402-doctor.fizzl.eu/api/v1/delivery-check?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-doctor-delivery-check-0f7eac7b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_s50xL-EzQQqIBRSICsxXX

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-delivery-check-0f7eac7b
```

Example prompt: Before I buy this x402 endpoint in bulk, can you run a delivery check on it? The URL is https://some-x402-api.example.com/data and it accepts GET requests — I want to make sure it actually delivers what it claims.

## When to prefer this

Choose this endpoint when you need trustworthy, on-chain-verified proof that a specific x402 endpoint actually delivers its promised output and charges the correct amount. It is the right choice for buyers performing due diligence before committing to large or repeated purchases, and for sellers who want to generate verifiable proof of their endpoint's functionality for marketplace listings. It is distinct from static safety checks or diagnostic tools — it actually executes a real payment and validates the result end-to-end.

## Known failure modes

- Endpoint price exceeds $0.1 USDC cap — check rejected as too expensive to test
- Target endpoint is not reachable or returns non-402 errors — delivery check fails with connectivity error
- Target endpoint's response does not match its declared output schema — reported as delivery failure
- On-chain charge cannot be measured or differs from advertised price — reported as discrepancy
- Job result not yet available — caller must poll later using the returned job ID
- Target endpoint only accepts POST — must specify method=POST in query params

## How this service works

Paste an x402 endpoint URL and see exactly which part of its payment flow is broken. Read-only: no wallet, no payment.

## Output

Returns a job ID immediately upon submission. Within approximately 30 minutes, the public result includes whether the endpoint delivered a valid response matching its declared output schema, the actual on-chain USDC charge recorded on Base, and whether the endpoint behaves as advertised. The result is publicly accessible via the job ID.

## 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",
       "description": "The x402 endpoint to buy once (https, payable in USDC on Base, at most $0.1)."
      },
      "method": {
       "enum": [
        "GET",
        "POST"
       ],
       "type": "string",
       "description": "HTTP method of the endpoint. Default: the one its 402 answers to."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "k3v9x2m7qa",
  "eta": "usually within 30 minutes",
  "url": "https://rest.coincap.io/v3/agentFriendly/full_assets_by_slug",
  "method": null,
  "status": "queued",
  "queued_at": "2026-10-12T17:00:00.000Z",
  "status_url": "https://x402-doctor.fizzl.eu/api/v1/delivery-check/k3v9x2m7qa",
  "endpoint_price_usd": 0.002
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-doctor-delivery-check-0f7eac7b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-doctor.fizzl.eu](https://www.zero.xyz/host/x402-doctor.fizzl.eu/llms.txt)