# x402 Merchant Audit – Price Drift Check

> x402 Merchant Audit – Price Drift Check is a paid API for AI agents from merchant-audit.clankerceo.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Live-probes an x402 paid API endpoint and checks for reachability, price drift, settlement history, and on-chain payment verification before you pay it.

## Facts

- Endpoint: GET https://merchant-audit.clankerceo.workers.dev/price-drift-check
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-merchant-audit-price-drift-check-dcc555da
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2_4YEWAjGR5xRyFf4zAZX

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-merchant-audit-price-drift-check-dcc555da
```

Example prompt: Before my agent pays it, audit the x402 endpoint at https://some-merchant.com/api/data — check if it's reachable, actually emits 402, has real settlement history, and flag any price drift.

## When to prefer this

Use this endpoint when an AI agent needs to autonomously vet an unknown or newly discovered x402 paid API before committing funds. It is the right choice over manual inspection when you need programmatic go/no-go signals (verdict + boolean checks) and on-chain corroboration of merchant legitimacy, especially for automated payment workflows where trust must be established without human review.

## Known failure modes

- Target URL unreachable — reachable flag returns false, verdict likely CAUTION or WARN
- Target does not emit HTTP 402 — emits_402 returns false, indicating it may not be a real x402 merchant
- No on-chain settlement data found — has_buyers false, onchain_inflow_usdc is 0
- Price drift detected — price_drift flag true, reasons will note the discrepancy
- Invalid or missing target query parameter — request fails with validation error
- Target URL uses HTTP instead of HTTPS — schema requires absolute https URL

## How this service works

Audit any x402 merchant before you pay it. Live probe, price-drift detection, settlement history and on-chain payment verification.

## Output

Returns a JSON object with a verdict (e.g. CAUTION, OK, WARN), a set of boolean checks (reachable, emits_402, has_buyers, price_drift) plus on-chain USDC inflow amount, and a human-readable reasons array explaining any concerns about the target x402 merchant.

## 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",
    "queryParams"
   ],
   "properties": {
    "type": {
     "enum": [
      "http"
     ],
     "type": "string"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "target"
     ],
     "properties": {
      "target": {
       "type": "string",
       "description": "Absolute https URL of the x402 resource to audit."
      }
     }
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "enum": [
      "json"
     ],
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "checks": {
   "emits_402": true,
   "reachable": true,
   "has_buyers": false,
   "price_drift": false,
   "onchain_inflow_usdc": 0
  },
  "target": "https://example-merchant.com/api/some-service",
  "reasons": [
   "listed but no settlements in 30d"
  ],
  "verdict": "CAUTION"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-merchant-audit-price-drift-check-dcc555da/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from merchant-audit.clankerceo.workers.dev](https://www.zero.xyz/host/merchant-audit.clankerceo.workers.dev/llms.txt)