ext-apps/examples/wiki-explorer-server/README.md
Jonathan Hefner 366c5d5a6b
Add wiki-explorer-server example (#122)
Interactive Wikipedia link graph visualization using force-graph with:
- Force-directed graph layout for exploring page connections
- Node expansion to reveal first-degree Wikipedia links
- Visual state tracking (blue=default, green=expanded, red=error)
- Direct browser access to Wikipedia pages

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Co-authored-by: Claude <noreply@anthropic.com>
2025-12-11 13:58:05 +01:00

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# 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.
<table>
<tr>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/01-zoomed.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/01-zoomed.png" alt="Zoomed" width="100%"></a></td>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/02-pop-up.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/02-pop-up.png" alt="Pop-up" width="100%"></a></td>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/03-expanded-graph.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/wiki-explorer-server/03-expanded-graph.png" alt="Expanded graph" width="100%"></a></td>
</tr>
</table>
## Features
- **Force-directed graph visualization**: Interactive graph powered by [`force-graph`](https://github.com/vasturiano/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:
```bash
npm install
```
2. Build and start the server:
```bash
npm run start:http # for Streamable HTTP transport
# OR
npm run start:stdio # for stdio transport
```
3. View using the [`basic-host`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/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:
```json
{
"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