ext-apps/examples/basic-server-vanillajs/server.ts
Jonathan Hefner 2109dccadb
Rewrite Quickstart guide with type-checked code examples
Rewrites the Quickstart tutorial to provide a more focused, step-by-step
introduction to building MCP Apps. The guide now uses synced code fences
that pull from `examples/quickstart/`, ensuring all code shown in the
documentation is type-checked and tested.

Key improvements:
- Clearer project setup instructions with explicit commands
- Streamlined explanations of the tool + resource registration pattern
- Added screenshot showing the completed app
- E2E test coverage validates the example works end-to-end

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-01-24 09:41:51 -06:00

64 lines
2.1 KiB
TypeScript

import { registerAppResource, registerAppTool, RESOURCE_MIME_TYPE } from "@modelcontextprotocol/ext-apps/server";
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import type { CallToolResult, ReadResourceResult } from "@modelcontextprotocol/sdk/types.js";
import fs from "node:fs/promises";
import path from "node:path";
import { z } from "zod";
// Works both from source (server.ts) and compiled (dist/server.js)
const DIST_DIR = import.meta.filename.endsWith(".ts")
? path.join(import.meta.dirname, "dist")
: import.meta.dirname;
/**
* Creates a new MCP server instance with tools and resources registered.
*/
export function createServer(): McpServer {
const server = new McpServer({
name: "Basic MCP App Server (Vanilla JS)",
version: "1.0.0",
});
// Two-part registration: tool + resource, tied together by the resource URI.
const resourceUri = "ui://get-time/mcp-app.html";
// Register a tool with UI metadata. When the host calls this tool, it reads
// `_meta.ui.resourceUri` to know which resource to fetch and render as an
// interactive UI.
registerAppTool(server,
"get-time",
{
title: "Get Time",
description: "Returns the current server time as an ISO 8601 string.",
inputSchema: {},
outputSchema: z.object({
time: z.string(),
}),
_meta: { ui: { resourceUri } }, // Links this tool to its UI resource
},
async (): Promise<CallToolResult> => {
const time = new Date().toISOString();
return {
content: [{ type: "text", text: time }],
structuredContent: { time },
};
},
);
// Register the resource, which returns the bundled HTML/JavaScript for the UI.
registerAppResource(server,
resourceUri,
resourceUri,
{ mimeType: RESOURCE_MIME_TYPE },
async (): Promise<ReadResourceResult> => {
const html = await fs.readFile(path.join(DIST_DIR, "mcp-app.html"), "utf-8");
return {
contents: [
{ uri: resourceUri, mimeType: RESOURCE_MIME_TYPE, text: html },
],
};
},
);
return server;
}