# HALOWERK Article Price Percentage Drop Detector

> HALOWERK Article Price Percentage Drop Detector is a paid API for AI agents from handel.halowerk.com, paid per call via x402, $0.007/call, status unknown (last checked 2026-10-10).

Fetches a product article's current price from a URL and calculates whether it has dropped by a specified percentage compared to a previously known price

## Facts

- Endpoint: POST https://handel.halowerk.com/v1/price/articles/percentage-drop?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-article-price-percentage-drop-detector-8a04c673
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_denv5KERhZCxG69zemiEu

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 halowerk-article-price-percentage-drop-detector-8a04c673 -d '<json body>'
```

Example prompt: Check whether the product at https://shop.example.com/articles/red-sneakers has dropped by at least 15% compared to its previous price of 89.99 USD, and let me know the result.

## When to prefer this

Use this endpoint when you need to programmatically detect price drops on specific article URLs against a previously known price and percentage threshold — especially in automated deal-detection pipelines, price alert workflows, or shopping agents. Prefer this over generic scraping when you want a structured, paid-per-call service with idempotency support and optional callback for async notification.

## Known failure modes

- URL is unreachable or returns non-200 response — endpoint may return an error or empty result
- Article page does not contain a parseable price — extraction fails
- Currency mismatch between previous price and current scraped price
- drop_percent must be greater than 0 and at most 100 — validation error if out of range
- previous.value must be between 0 and 1,000,000,000 — error if exceeded
- idempotency_key too short (min 32 chars) or contains invalid characters
- Payment failure via x402 protocol prevents request from being processed

## How this service works

Notify when a listed-price reduction reaches a chosen percentage; previous price must be positive. Uses an optional predicate extension of the proven Price-Callback motor. price_percentage_drop_decision records this exact rule; the rule executes BEFORE dispatch. Same public IPv4HTTPS pinned connections, robots checks,9s,1MiBHTML,at-most-once receipt/idempotency7days,failureschargedfalse. Caller supplies historical price and schedules polling.

## Output

A JSON response indicating whether the article's current price has dropped by the specified percentage relative to the provided previous price, likely including the current price, the calculated drop percentage, and a boolean or signal confirming whether the threshold was met.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048
  },
  "previous": {
   "type": "object",
   "required": [
    "value",
    "currency"
   ],
   "properties": {
    "value": {
     "type": "number",
     "maximum": 1000000000,
     "minimum": 0
    },
    "currency": {
     "type": "string",
     "pattern": "^[A-Z]{3}$"
    }
   },
   "additionalProperties": false
  },
  "callback_url": {
   "type": "string",
   "maxLength": 2048
  },
  "drop_percent": {
   "type": "number",
   "maximum": 100,
   "exclusiveMinimum": 0
  },
  "idempotency_key": {
   "type": "string",
   "pattern": "^[A-Za-z0-9_-]+$",
   "maxLength": 128,
   "minLength": 32
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-article-price-percentage-drop-detector-8a04c673/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from handel.halowerk.com](https://www.zero.xyz/host/handel.halowerk.com/llms.txt)