# Blackhull x402 Service Flag Checker

> Blackhull x402 Service Flag Checker is a paid API for AI agents from blackhullsystems.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-31).

Returns compliance flags and a grade for a given x402 resource URL, indicating whether the service behaves as listed and meets quality standards.

## Facts

- Endpoint: GET https://blackhullsystems.com/flags?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/blackhull-x402-service-flag-checker-1034a0c7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iA5uXgHqLMgSJyQLo-g2T

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 blackhull-x402-service-flag-checker-1034a0c7
```

Example prompt: Check the Blackhull flags for this x402 service — https://someprovider.com/api/endpoint — and tell me if it's clean or has any compliance issues before I start using it.

## When to prefer this

Use this endpoint when you need a quick, structured trust signal on a specific x402 resource URL before routing agent payments to it. It is purpose-built for the x402 micropayment ecosystem and returns machine-readable compliance codes and grades, making it ideal for automated pre-payment screening in agent workflows. Prefer it over general web-reputation tools when the target is specifically an x402-gated API.

## Known failure modes

- URL not found in Blackhull's index — returns empty codes array or unknown grade
- Malformed or missing 'url' query parameter — likely a 400-level error
- x402 service too new to have been assessed — may return no flags yet
- Network timeout contacting blackhullsystems.com — no response

## How this service works

Blackhull measures the agent economy and sells AI agents the check they run before they pay another service.

## Output

A JSON object containing an array of code objects (each with a 'code' string like 'PAID_AS_LISTED' and a 'severity' label such as 'positive', 'warning', or 'negative') plus a top-level 'grade' field summarizing the overall compliance status (e.g. 'CLEAN').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "the x402 resource URL"
      }
     }
    }
   }
  },
  "output": {
   "type": "object",
   "properties": {
    "type": {
     "const": "json"
    },
    "schema": {
     "type": "object"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "codes": [
   {
    "code": "PAID_AS_LISTED",
    "severity": "positive"
   }
  ],
  "grade": "CLEAN"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/blackhull-x402-service-flag-checker-1034a0c7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from blackhullsystems.com](https://www.zero.xyz/host/blackhullsystems.com/llms.txt)