MCP Base Server

# ツール実装の完全な例 ## 基本的なツール実装 ```typescript import { z } from 'zod'; import { ToolDefinition } from '../../types/mcp.js'; // 入力スキーマ定義 export const CalculatorInputSchema = z.object({ operation: z.enum(['add', 'subtract', 'multiply', 'divide']), a: z.number(), b: z.number() }).strict(); export type CalculatorInput = z.infer<typeof CalculatorInputSchema>; // MCPツール定義 export const toolDefinition: ToolDefinition = { name: 'calculator', description: 'Performs basic mathematical operations', inputSchema: { type: 'object' as const, properties: { operation: { type: 'string', enum: ['add', 'subtract', 'multiply', 'divide'], description: 'The mathematical operation to perform' }, a: { type: 'number', description: 'The first number' }, b: { type: 'number', description: 'The second number' } }, required: ['operation', 'a', 'b'], additionalProperties: false } }; // 出力スキーマ定義 export const CalculatorOutputSchema = z.object({ result: z.number(), operation: z.string(), inputs: z.object({ a: z.number(), b: z.number() }) }); export type CalculatorOutput = z.infer<typeof CalculatorOutputSchema>; // ツール実装 export async function calculator(input: CalculatorInput): Promise<CalculatorOutput> { let result: number; switch (input.operation) { case 'add': result = input.a + input.b; break; case 'subtract': result = input.a - input.b; break; case 'multiply': result = input.a * input.b; break; case 'divide': if (input.b === 0) { throw new Error('Division by zero is not allowed'); } result = input.a / input.b; break; default: throw new Error(`Unsupported operation: ${input.operation}`); } return { result, operation: input.operation, inputs: { a: input.a, b: input.b } }; } ``` ## 外部API連携ツールの例 ```typescript import axios from 'axios'; export const WeatherInputSchema = z.object({ city: z.string().min(1, 'City name is required'), units: z.enum(['metric', 'imperial']).optional().default('metric') }).strict(); export type WeatherInput = z.infer<typeof WeatherInputSchema>; export const toolDefinition: ToolDefinition = { name: 'get_weather', description: 'Gets current weather information for a city', inputSchema: { type: 'object' as const, properties: { city: { type: 'string', description: 'The name of the city' }, units: { type: 'string', enum: ['metric', 'imperial'], description: 'Temperature units (metric or imperial)', default: 'metric' } }, required: ['city'], additionalProperties: false } }; export const WeatherOutputSchema = z.object({ city: z.string(), temperature: z.number(), description: z.string(), humidity: z.number(), units: z.string() }); export type WeatherOutput = z.infer<typeof WeatherOutputSchema>; export async function getWeather(input: WeatherInput): Promise<WeatherOutput> { try { const apiKey = process.env.WEATHER_API_KEY; if (!apiKey) { throw new Error('WEATHER_API_KEY environment variable is not set'); } const response = await axios.get( `https://api.openweathermap.org/data/2.5/weather`, { params: { q: input.city, appid: apiKey, units: input.units } } ); const data = response.data; return { city: data.name, temperature: data.main.temp, description: data.weather[0].description, humidity: data.main.humidity, units: input.units }; } catch (error) { if (axios.isAxiosError(error)) { throw new Error(`Weather API error: ${error.response?.data?.message || error.message}`); } throw new Error(`Failed to get weather data: ${error instanceof Error ? error.message : String(error)}`); } } ```