progressExample.ts

/**
 * Example: Progress notifications over stdio.
 *
 * Demonstrates a tool that reports progress to the client while processing.
 *
 * Run:
 *   npx tsx src/examples/server/progressExample.ts
 *
 * Then connect a client with an `onprogress` callback (see docs/protocol.md).
 */

import { McpServer } from '../../server/mcp.js';
import { StdioServerTransport } from '../../server/stdio.js';
import { z } from 'zod';

const server = new McpServer({ name: 'progress-example', version: '1.0.0' }, { capabilities: { logging: {} } });

server.registerTool(
    'count',
    {
        description: 'Count to N with progress updates',
        inputSchema: { n: z.number().int().min(1).max(100) }
    },
    async ({ n }, extra) => {
        for (let i = 1; i <= n; i++) {
            if (extra.signal.aborted) {
                return { content: [{ type: 'text', text: `Cancelled at ${i}` }], isError: true };
            }

            if (extra._meta?.progressToken !== undefined) {
                await extra.sendNotification({
                    method: 'notifications/progress',
                    params: {
                        progressToken: extra._meta.progressToken,
                        progress: i,
                        total: n,
                        message: `Counting: ${i}/${n}`
                    }
                });
            }

            // Simulate work
            await new Promise(resolve => setTimeout(resolve, 100));
        }

        return { content: [{ type: 'text', text: `Counted to ${n}` }] };
    }
);

async function main() {
    const transport = new StdioServerTransport();
    await server.connect(transport);
}

main().catch(error => {
    console.error('Server error:', error);
    process.exit(1);
});