mcpServerOutputSchema.ts

#!/usr/bin/env node
/**
 * Example MCP server using the high-level McpServer API with outputSchema
 * This demonstrates how to easily create tools with structured output
 */

import { McpServer, StdioServerTransport } from '@modelcontextprotocol/server';
import * as z from 'zod/v4';

const server = new McpServer({
    name: 'mcp-output-schema-high-level-example',
    version: '1.0.0'
});

// Define a tool with structured output - Weather data
server.registerTool(
    'get_weather',
    {
        description: 'Get weather information for a city',
        inputSchema: z.object({
            city: z.string().describe('City name'),
            country: z.string().describe('Country code (e.g., US, UK)')
        }),
        outputSchema: z.object({
            temperature: z.object({
                celsius: z.number(),
                fahrenheit: z.number()
            }),
            conditions: z.enum(['sunny', 'cloudy', 'rainy', 'stormy', 'snowy']),
            humidity: z.number().min(0).max(100),
            wind: z.object({
                speed_kmh: z.number(),
                direction: z.string()
            })
        })
    },
    async ({ city, country }) => {
        // Parameters are available but not used in this example
        void city;
        void country;
        // Simulate weather API call
        const temp_c = Math.round((Math.random() * 35 - 5) * 10) / 10;
        const conditions = ['sunny', 'cloudy', 'rainy', 'stormy', 'snowy'][Math.floor(Math.random() * 5)];

        const structuredContent = {
            temperature: {
                celsius: temp_c,
                fahrenheit: Math.round(((temp_c * 9) / 5 + 32) * 10) / 10
            },
            conditions,
            humidity: Math.round(Math.random() * 100),
            wind: {
                speed_kmh: Math.round(Math.random() * 50),
                direction: ['N', 'NE', 'E', 'SE', 'S', 'SW', 'W', 'NW'][Math.floor(Math.random() * 8)]
            }
        };

        return {
            content: [
                {
                    type: 'text',
                    text: JSON.stringify(structuredContent, null, 2)
                }
            ],
            structuredContent
        };
    }
);

async function main() {
    const transport = new StdioServerTransport();
    await server.connect(transport);
    console.error('High-level Output Schema Example Server running on stdio');
}

try {
    await main();
} catch (error) {
    console.error('Server error:', error);
    // eslint-disable-next-line unicorn/no-process-exit
    process.exit(1);
}