Math Calculator MCP Server

import express from "express"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js"; import { createMcpServer } from "./server.js"; import { randomUUID } from "node:crypto"; const args = process.argv.slice(2); // Vercel sets the VERCEL environment variable to '1' const isVercel = process.env.VERCEL === '1'; const mode = (isVercel || args.includes("http")) ? "http" : "stdio"; if (mode === "http") { const app = express(); const transports: Record<string, StreamableHTTPServerTransport> = {}; app.use(express.json()); // Handle SSE (GET) app.get("/mcp", async (req, res) => { const sessionId = req.headers["mcp-session-id"] as string; if (!sessionId || !transports[sessionId]) { res.status(400).send("Invalid or missing session ID"); return; } const transport = transports[sessionId]; await transport.handleRequest(req, res); }); // Handle Messages (POST) app.post("/mcp", async (req, res) => { const sessionId = req.headers["mcp-session-id"] as string; let transport: StreamableHTTPServerTransport | undefined; if (sessionId) { transport = transports[sessionId]; } if (!transport) { // Check for initialization const body = req.body; // Simple check for initialize message if (body && typeof body === 'object' && body.method === 'initialize') { transport = new StreamableHTTPServerTransport({ sessionIdGenerator: () => randomUUID(), onsessioninitialized: (id) => { if (transport) transports[id] = transport; console.log(`Session initialized: ${id}`); }, onsessionclosed: (id) => { delete transports[id]; console.log(`Session closed: ${id}`); } }); const server = createMcpServer(); await server.connect(transport); // Handle the request await transport.handleRequest(req, res, body); return; } } if (!transport) { res.status(400).json({ jsonrpc: "2.0", error: { code: -32000, message: "Session not found. Send an 'initialize' request first." }, id: null }); return; } await transport.handleRequest(req, res, req.body); }); const port = process.env.PORT || 3000; app.listen(port, () => { console.log(`MCP Server running on http://localhost:${port}/mcp`); console.log("Supports SSE and Streamable HTTP transports."); }); } else { // Stdio Mode (async () => { const server = createMcpServer(); const transport = new StdioServerTransport(); await server.connect(transport); // console.log is intercepted by StdioTransport, so use console.error for logs console.error("MCP Server running on stdio"); })(); }