Example: Wiki Explorer

Visualizes Wikipedia link graphs using a force-directed layout. Explore how Wikipedia pages are connected by expanding nodes to reveal first-degree links.

MCP Client Configuration

Add to your MCP client configuration (stdio transport):

{
  "mcpServers": {
    "wiki-explorer": {
      "command": "npx",
      "args": [
        "-y",
        "--silent",
        "--registry=https://registry.npmjs.org/",
        "@modelcontextprotocol/server-wiki-explorer",
        "--stdio"
      ]
    }
  }
}

Local Development

To test local modifications, use this configuration (replace ~/code/ext-apps with your clone path):

{
  "mcpServers": {
    "wiki-explorer": {
      "command": "bash",
      "args": [
        "-c",
        "cd ~/code/ext-apps/examples/wiki-explorer-server && npm run build >&2 && node dist/index.js --stdio"
      ]
    }
  }
}

Features

• Force-directed graph visualization: Interactive graph powered by force-graph
• Node expansion: Click any node to expand and see all pages it links to
• Visual state tracking: Nodes change color based on state (blue = default, green = expanded, red = error)
• Direct page access: Open any Wikipedia page in your browser

Running

1. Install dependencies:

   npm install

2. Build and start the server:

   npm run start:http  # for Streamable HTTP transport
   # OR
   npm run start:stdio  # for stdio transport

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

Tool Input

To test the example, call the get-first-degree-links tool with a Wikipedia URL:

{
  "url": "https://en.wikipedia.org/wiki/Graph_theory"
}

Click nodes in the graph to Open (view in browser) or Expand (visualize linked pages).

Architecture

Server (server.ts)

MCP server that fetches Wikipedia pages and extracts internal links.

Exposes one tool:

• get-first-degree-links - Returns links to other Wikipedia pages from a given page

App (src/mcp-app.ts)

Vanilla TypeScript app using force-graph for visualization that:

• Receives tool inputs via the MCP App SDK
• Renders an interactive force-directed graph
• Supports node expansion to explore link relationships