# x402-tools Null Hold 21 Diagnostic Endpoint

> x402-tools Null Hold 21 Diagnostic Endpoint is a paid API for AI agents from openclawproductions.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-11).

Returns a paid diagnostic JSON payload for SKU 'nullhold21' to test x402 HTTP payment flow and EIP-3009 authorization

## Facts

- Endpoint: GET https://openclawproductions.com/api/v1/nullhold21?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-tools-null-hold-21-diagnostic-endpoint-7836d62e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VD6jjnxtobxdoG0ZmJyIG

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-tools-null-hold-21-diagnostic-endpoint-7836d62e
```

Example prompt: Run the x402 nullhold21 diagnostic against the OpenX402 facilitator so I can confirm my EIP-3009 payment authorization is working and see the paid JSON response shape.

## When to prefer this

Use this endpoint when you need a minimal, low-cost ($0.02 USDC) live test of the x402 HTTP payment protocol with OpenX402 as the facilitator, especially to validate EIP-3009 authorization flows, inspect the HTTP 402 response shape, or confirm end-to-end micropayment gating before deploying your own x402-gated service.

## Known failure modes

- HTTP 402 returned when no valid x402 payment header is provided — expected behavior for unpaid requests
- Payment rejected if EIP-3009 authorization signature is malformed or expired
- OpenX402 facilitator unavailable returns 5xx error
- Invalid or missing properties parameter may return 400 bad request
- USDC insufficient balance causes payment failure before response is returned

## How this service works

Paid x402 diagnostics. Unpaid paid-SKU requests return HTTP 402 with eip3009 extras. Facilitator: OpenX402 only.

## Output

A JSON object containing the SKU identifier ('nullhold21'), a human-readable title ('Null Hold 21'), the price ('$0.02'), and a note clarifying the payload shape. On unpaid requests, returns HTTP 402 with EIP-3009 payment extension headers indicating where and how to pay.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "sku": "nullhold21",
  "note": "Example paid JSON shape. Not a live settle.",
  "price": "$0.02",
  "title": "Null Hold 21"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-tools-null-hold-21-diagnostic-endpoint-7836d62e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from openclawproductions.com](https://www.zero.xyz/host/openclawproductions.com/llms.txt)