examples/basic-server-react/README.md

Example: Basic Server (React)

An MCP App example with a React UI.

Looking for a vanilla JavaScript example? See basic-server-vanillajs!

Overview

• Tool registration with a linked UI resource
• React UI using the useApp() hook
• App communication APIs: callServerTool, sendMessage, sendLog, openLink

Key Files

• server.ts - MCP server with tool and resource registration
• mcp-app.html / src/mcp-app.tsx - React UI using useApp() hook

Getting Started

npm install
npm run dev

How It Works

1. The server registers a get-time tool with metadata linking it to a UI HTML resource (ui://get-time/mcp-app.html).
2. When the tool is invoked, the Host renders the UI from the resource.
3. The UI uses the MCP App SDK API to communicate with the host and call server tools.

Build System

This example bundles into a single HTML file using Vite with vite-plugin-singlefile — see vite.config.ts. This allows all UI content to be served as a single MCP resource. Alternatively, MCP apps can load external resources by defining _meta.ui.csp.resourceDomains in the UI resource metadata.