ext-apps/examples/system-monitor-server

Example: System Monitor App

A demo MCP App that displays real-time OS metrics with a stacked area chart for per-core CPU usage and a bar gauge for memory.

Features

• Per-Core CPU Monitoring: Stacked area chart showing individual CPU core utilization over a 1-minute sliding window
• Memory Usage: Horizontal bar gauge with color-coded thresholds (green/yellow/red)
• System Info: Hostname, platform, and uptime display
• Auto-Polling: Automatically starts monitoring on load with 2-second refresh interval
• Theme Support: Adapts to light/dark mode preferences

Running

1. Install dependencies:

   npm install
   

2. Build and start the server:

   npm start
   

   The server will listen on http://localhost:3001/mcp.

3. View using the basic-host example or another MCP Apps-compatible host.

Architecture

Server (server.ts)

Exposes a single get-system-stats tool that returns:

• Raw per-core CPU timing data (idle/total counters)
• Memory usage (used/total/percentage)
• System info (hostname, platform, uptime)

The tool is linked to a UI resource via _meta[RESOURCE_URI_META_KEY].

App (src/mcp-app.ts)

• Uses Chart.js for the stacked area chart visualization
• Polls the server tool every 2 seconds
• Computes CPU usage percentages client-side from timing deltas
• Maintains a 30-point history (1 minute at 2s intervals)
• Updates all UI elements on each poll