61cd4ed219
Not all MCP clients support structuredContent in MCP tool results, so
examples now return data as JSON in content and parse it client-side.
Pattern used:
- Server: content: [{ type: "text", text: JSON.stringify(data) }]
- Client: JSON.parse(result.content!.filter(...).map(...).join(""))
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
101 lines
2.9 KiB
TypeScript
101 lines
2.9 KiB
TypeScript
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
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import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
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import type { CallToolResult, ReadResourceResult } from "@modelcontextprotocol/sdk/types.js";
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import cors from "cors";
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import express, { type Request, type Response } from "express";
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import fs from "node:fs/promises";
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import path from "node:path";
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import { RESOURCE_URI_META_KEY } from "../../dist/src/app";
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const PORT = process.env.PORT ? parseInt(process.env.PORT, 10) : 3001;
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const DIST_DIR = path.join(import.meta.dirname, "dist");
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const server = new McpServer({
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name: "MCP App Server",
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version: "1.0.0",
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});
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// MCP Apps require two-part registration: a tool (what the LLM calls) and a
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// resource (the UI it renders). The `_meta` field on the tool links to the
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// resource URI, telling hosts which UI to display when the tool executes.
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{
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const resourceUri = "ui://get-time/mcp-app.html";
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server.registerTool(
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"get-time",
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{
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title: "Get Time",
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description: "Returns the current server time as an ISO 8601 string.",
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inputSchema: {},
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_meta: { [RESOURCE_URI_META_KEY]: resourceUri },
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},
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async (): Promise<CallToolResult> => {
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const time = new Date().toISOString();
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return {
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content: [{ type: "text", text: JSON.stringify({ time }) }],
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};
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},
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);
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server.registerResource(
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resourceUri,
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resourceUri,
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{},
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async (): Promise<ReadResourceResult> => {
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const html = await fs.readFile(path.join(DIST_DIR, "mcp-app.html"), "utf-8");
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return {
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contents: [
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// Per the MCP App specification, "text/html;profile=mcp-app" signals
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// to the Host that this resource is indeed for an MCP App UI.
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{ uri: resourceUri, mimeType: "text/html;profile=mcp-app", text: html },
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],
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};
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},
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);
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}
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const app = express();
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app.use(cors());
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app.use(express.json());
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app.post("/mcp", async (req: Request, res: Response) => {
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try {
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const transport = new StreamableHTTPServerTransport({
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sessionIdGenerator: undefined,
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enableJsonResponse: true,
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});
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res.on("close", () => { transport.close(); });
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await server.connect(transport);
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await transport.handleRequest(req, res, req.body);
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} catch (error) {
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console.error("Error handling MCP request:", error);
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if (!res.headersSent) {
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res.status(500).json({
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jsonrpc: "2.0",
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error: { code: -32603, message: "Internal server error" },
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id: null,
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});
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}
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}
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});
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const httpServer = app.listen(PORT, () => {
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console.log(`Server listening on http://localhost:${PORT}/mcp`);
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});
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function shutdown() {
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console.log("\nShutting down...");
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httpServer.close(() => {
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console.log("Server closed");
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process.exit(0);
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});
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}
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process.on("SIGINT", shutdown);
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process.on("SIGTERM", shutdown);
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