# x402 Bazaar Listing Monitor [Health: Active]

**Category:** 💰 Finance & Fintech  
**Repository:** https://github.com/acjlabs/x402-listing-monitor  
**GitHub Stars:** 1  
**Views:** 1  
**Installs:** 0  
**Upvotes:** 0  
**Directory Page:** https://allmcps.com/mcp/x402-bazaar-listing-monitor

## Description
Checks x402 Bazaar resource listings against the public discovery catalog and flags drops.

## Tools
Capabilities this server exposes over MCP:

- **check_listing_health** — Checks whether a seller's x402 Bazaar resources are currently listed under the given payTo address in the public discovery catalog. Flags each resource as listed or missing — the same per-seller diff the registered poller runs on a schedule, run once on demand for a payTo/resources pair whether or not it has been registered with this service.

## Claude Desktop Quick Installation
Remote MCP endpoint (confidence: high). Install path detected from listing signals. Add as a URL/SSE server in your client:

```json
"mcpServers": {
  "x402-bazaar-listing-monitor": {
    "url": "https://x402-listing-monitor.acjlabs.com/mcp"
  }
}
```

## Documentation

## What x402 Bazaar Listing Monitor does

The x402 Bazaar Listing Monitor watches x402 resources that sellers associate with a `payTo` address. It compares the resources you declare with Coinbase CDP’s public Bazaar discovery catalog and identifies resources that are listed, missing, or associated with a mismatched payment address.

The hosted service keeps a timestamped record of observed state changes. It can report when a resource disappears, remains absent after the indexing-lag grace period, or returns to the catalog. The repository documents the hosted service; its implementation is not open source.

## How it works

Register a seller record with a unique `sellerId`, a valid `payTo` address, and between one and 200 HTTPS or HTTP resource URLs. A scheduled poll runs every six hours for registered sellers. Each run compares the declared resources with the live discovery response and updates the seller’s status.

A resource that remains absent for at least three consecutive polls produces one “still missing” alert for that miss streak. If it returns and later disappears again, the new absence is treated as a separate streak. The current status and recent alert history are available through the HTTP API.

The x402 Bazaar Listing Monitor also accepts an on-demand MCP request for any valid `payTo` and resource list, whether or not that pair has been registered. The service applies per-IP rate limits to registration, status, polling, and MCP requests.

## Setup and configuration

Use the hosted streamable-HTTP MCP endpoint at `https://x402-listing-monitor.acjlabs.com/mcp`. No signup or API key is required for the documented MCP tool.

For scheduled monitoring, call `POST /register` with a seller ID, payment address, resource URLs, and optionally an HTTPS webhook URL. Seller IDs must be 2–64 characters and may contain letters, digits, hyphens, and underscores. The payment address must be a `0x`-prefixed 40-character hexadecimal value. Duplicate resource URLs are not accepted, and an existing seller ID cannot be overwritten.

Webhook delivery is optional. Any 2xx response counts as delivered; redirects are not followed, and failed deliveries are not retried. `alertEmail` can be stored during registration, but email delivery is not enabled. Without a contact method, use `GET /status` to inspect results.

## Tools and capabilities

The MCP tool is `check_listing_health`. It accepts:

- `payTo`: a `0x`-prefixed 40-hex-character address.
- `resources`: an array of 1–200 HTTP or HTTPS URLs.

It returns JSON identifying each resource as listed or missing. The x402 Bazaar Listing Monitor’s HTTP API additionally provides a liveness endpoint, registration, status lookup, and an endpoint that starts a poll for all registered sellers.

`GET /status` requires both the registered seller ID and matching payment address. It reports each resource’s state, consecutive misses, last check time, recent alerts, and delivery status. `POST /poll` returns aggregate counts only and responds with HTTP 409 when another poll is already running.

## Limitations and notes

Monitoring is based on self-declared resources: the service checks the URLs you register or submit to the MCP tool. It does not establish that those resources are actually served by the seller.

The catalog and the monitor can observe temporary indexing delays. For that reason, the recurring-missing alert waits for three consecutive missed polls and fires once per miss streak. Alert records are written before delivery, but an undelivered webhook is not retried automatically.

The service is an early release. Webhook alerts are available, while email notifications are not. The status endpoint is a knowledge check rather than authentication, and its data reflects a diff against a public catalog. Additional paid-tier alert types and shorter polling intervals are documented, but their availability depends on the applicable plan.

_Full upstream README: https://allmcps.com/mcp/x402-bazaar-listing-monitor/readme_