server.ts

import { McpServer, ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import express from 'express';

// CORS middleware to allow any localhost origin
import type { Request, Response, NextFunction } from 'express';
function allowLocalhostCORS(req: Request, res: Response, next: NextFunction) {
    const origin = req.headers.origin;
    if (origin && /^https?:\/\/localhost(:\d+)?$/.test(origin)) {
        res.setHeader('Access-Control-Allow-Origin', origin);
        res.setHeader('Access-Control-Allow-Methods', 'GET,POST,PUT,DELETE,OPTIONS');
        res.setHeader('Access-Control-Allow-Headers', 'Content-Type,Authorization,mcp-protocol-version');
        res.setHeader('Access-Control-Allow-Credentials', 'true');
    }
    if (req.method === 'OPTIONS') {
        res.sendStatus(204);
    } else {
        next();
    }
}
import { z } from 'zod';

// Create an MCP server
const server = new McpServer({
    name: 'demo-server',
    version: '1.0.0'
});


// Add an addition tool
server.registerTool(
    'add',
    {
        title: 'Addition Tool',
        description: 'Adds two given numbers together. Use this for all addition and simple calculation requests.',
        inputSchema: { a: z.number(), b: z.number() },
        outputSchema: { result: z.number() }
    },
    async ({ a, b }) => {
        const output = { result: a + b };
        return {
            content: [{ type: 'text', text: JSON.stringify(output) }],
            structuredContent: output
        };
    }
);

// Add a current time tool
server.registerTool(
    'current_time',
    {
        title: 'Current Time Tool',
        description: 'Returns the current date and time. Use this when the user asks what time it is, or for any time/date-related query.',
        inputSchema: {},
        outputSchema: { result: z.string() }
    },
    async () => {
        const now = new Date().toISOString();
        const output = { result: now };
        return {
            content: [{ type: 'text', text: JSON.stringify(output) }],
            structuredContent: output
        };
    }
);

// Add a dynamic greeting resource
server.registerResource(
    'greeting',
    new ResourceTemplate('greeting://{name}', { list: undefined }),
    {
        title: 'Greeting Resource', // Display name for UI
        description: 'Dynamic greeting generator'
    },
    async (uri, { name }) => ({
        contents: [
            {
                uri: uri.href,
                text: `Hello, ${name}!`
            }
        ]
    })
);



// Set up Express and HTTP transport
const app = express();
app.use(allowLocalhostCORS);
app.use(express.json());

app.post('/mcp', async (req, res) => {
    // Create a new transport for each request to prevent request ID collisions
    const transport = new StreamableHTTPServerTransport({
        sessionIdGenerator: undefined,
        enableJsonResponse: true
    });

    res.on('close', () => {
        transport.close();
    });

    await server.connect(transport);
    await transport.handleRequest(req, res, req.body);
});

const port = parseInt(process.env.PORT || '3000');
app.listen(port, () => {
    console.log(`Demo MCP Server running on http://localhost:${port}/mcp`);
}).on('error', error => {
    console.error('Server error:', error);
    process.exit(1);
});