# mcp-page-monitor

MCP server for monitoring web page changes. Uses Playwright to capture page content, SQLite for snapshot storage, and optional LLM integration for business impact analysis.

Available on [npm](https://www.npmjs.com/package/mcp-page-monitor) and the [MCPize marketplace](https://mcpize.com).

## Tools

### `monitor_page`

Register a URL to watch for changes. Takes an initial snapshot immediately.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `url` | string | yes | URL to monitor |
| `label` | string | no | Human-readable label |
| `selector` | string | no | CSS selector to monitor a specific element |
| `check_interval_minutes` | number | no | Check frequency (1–10080). Default: 60 |

### `check_changes`

Browse a monitored URL with Playwright, capture current content, and diff against the stored snapshot.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `url` | string | yes | URL to check (must be registered first) |

Returns `{ changed, diff, timestamp }` — diff includes added/removed line counts, changed sections, and a unified diff string.

### `analyze_change`

Analyze a page diff using an LLM to summarize what changed and assess business impact.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `url` | string | yes | URL whose changes to analyze |
| `diff_text` | string | no | Provide diff text directly instead of computing from snapshots |

Returns `{ summary, impact, severity }` — severity is `low | medium | high | critical`.

Falls back to deterministic analysis (pattern matching for pricing changes, errors, policy updates, etc.) when no LLM endpoint is configured.

### `list_monitored_pages`

List all URLs currently being monitored.

### `remove_monitored_page`

Stop monitoring a URL.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `url` | string | yes | URL to stop monitoring |

## Installation

```bash
npm install mcp-page-monitor
```

Or run directly:

```bash
npx mcp-page-monitor
```

### Requirements

- Node.js 22+
- Chromium browser (Playwright uses it for page rendering)

Install Playwright browsers if needed:

```bash
npx playwright install chromium
```

## Configuration

### Claude Desktop / Cursor / MCP Client

Add to your MCP client config:

```json
{
  "mcpServers": {
    "page-monitor": {
      "command": "npx",
      "args": ["mcp-page-monitor"],
      "env": {
        "PLAYWRIGHT_CHROMIUM_PATH": "/usr/bin/chromium-browser"
      }
    }
  }
}
```

### Environment Variables

| Variable | Default | Description |
|----------|---------|-------------|
| `PAGE_MONITOR_DB_PATH` | `~/.mcp-page-monitor/page-monitor.db` | SQLite database location |
| `PLAYWRIGHT_CHROMIUM_PATH` | `/usr/bin/chromium-browser` | Path to Chromium executable |
| `CHROME_PATH` | — | Fallback browser path |
| `PAGE_TIMEOUT_MS` | `30000` | Page navigation timeout |
| `LLM_ENDPOINT` | — | LLM API endpoint for `analyze_change` (e.g. OpenAI-compatible `/v1/chat/completions`) |
| `LLM_API_KEY` | — | Bearer token for LLM endpoint |
| `LLM_MODEL_ID` | `gpt-4o-mini` | Model to use for analysis |
| `LLM_SOURCE_SYSTEM` | `mcp-page-monitor` | Source identifier sent to LLM |

## How It Works

1. **Register** a page with `monitor_page` — takes an initial snapshot via headless Chromium
2. **Check** for changes with `check_changes` — fetches current content and computes a line-level diff (LCS-based) against the last snapshot
3. **Analyze** changes with `analyze_change` — sends the diff to an LLM for business impact assessment, or uses built-in heuristics (pricing detection, error detection, policy changes) when no LLM is available

All snapshots are stored in a local SQLite database with WAL mode enabled for concurrent access.

## Development

```bash
git clone https://github.com/deialedin/mcp-page-monitor
cd mcp-page-monitor
npm install
npm run build       # Compile TypeScript
npm test            # Run 26 tests
npm run dev         # Watch mode with tsx
```

## License

MIT