MCP Base Server

# ToolHandler実装例 ## 基本的な実装パターン ```typescript import { ErrorCode, McpError } from '@modelcontextprotocol/sdk/types.js'; export class ToolHandler { private validateAndParseInput<T>( args: unknown, schema: any, toolName: string ): T { try { return schema.parse(args || {}); } catch (error) { throw new McpError( ErrorCode.InvalidParams, `Invalid parameters for ${toolName}: ${error instanceof Error ? error.message : String(error)}` ); } } private formatResponse(result: any) { return { content: [ { type: 'text' as const, text: JSON.stringify(result, null, 2) } ] }; } async executeTool(name: string, args: unknown) { switch (name) { case 'example_tool': { // バリデーションを経たツール実行 const input = this.validateAndParseInput<ExampleToolInput>( args, ExampleToolInputSchema, 'example_tool' ); const result = await exampleTool(input); return this.formatResponse(result); } default: throw new McpError( ErrorCode.MethodNotFound, `Unknown tool: ${name}` ); } } } ``` ## カスタムクライアント統合例 ```typescript export class ToolHandler { private customClient: CustomClient | null = null; private async ensureCustomClient(): Promise<CustomClient> { if (!this.customClient) { const apiKey = process.env.API_KEY; if (!apiKey) { throw new McpError( ErrorCode.InvalidRequest, 'API_KEY environment variable is not set' ); } this.customClient = new CustomClient(apiKey); } return this.customClient; } async executeTool(name: string, args: unknown) { const client = await this.ensureCustomClient(); switch (name) { case 'api_tool': { const input = this.validateAndParseInput<ApiToolInput>( args, ApiToolInputSchema, 'api_tool' ); const result = await apiTool(client, input); return this.formatResponse(result); } // ... } } } ```