Simple MCP Server

Instructions

Implementation Reference

• src/index.ts:374-400 (handler)

  The main handler function for the 'list_directory' tool. It validates the input directory path using PathValidator, lists the directory contents with fs.readdir (including file types), formats the output with directory/file icons, and returns a formatted CallToolResult.

  private async listDirectory(dirpath: string): Promise<CallToolResult> {
    try {
      const pathValidation = this.pathValidator.validatePath(dirpath);
      if (!pathValidation.isValid) {
        throw new Error(pathValidation.error);
      }
  
      console.error(`Listing directory: ${pathValidation.normalizedPath}`);
      const items = await fs.readdir(pathValidation.normalizedPath, { withFileTypes: true });
      const fileList = items.map(item => {
        const type = item.isDirectory() ? "📁" : "📄";
        return `${type} ${item.name}`;
      });
  
      return {
        content: [
          {
            type: "text",
            text: `ディレクトリ "${pathValidation.normalizedPath}" の内容:\n\n${fileList.join("\n")}`,
          },
        ],
        isError: false,
      };
    } catch (error) {
      throw new Error(`ディレクトリの一覧取得に失敗: ${error}`);
    }
  }

• src/index.ts:150-159 (schema)

  The input schema definition for the 'list_directory' tool, specifying an object with a required 'dirpath' string property.

  inputSchema: {
    type: "object",
    properties: {
      dirpath: {
        type: "string",
        description: "一覧表示するディレクトリのパス",
      },
    },
    required: ["dirpath"],
  },

• src/index.ts:147-160 (registration)

  Registration of the 'list_directory' tool in the TOOLS array, which is returned by the ListToolsRequestSchema handler. Includes name, description, and input schema.

  {
    name: "list_directory",
    description: "指定されたディレクトリの内容を一覧表示します（許可されたディレクトリのみ）",
    inputSchema: {
      type: "object",
      properties: {
        dirpath: {
          type: "string",
          description: "一覧表示するディレクトリのパス",
        },
      },
      required: ["dirpath"],
    },
  },

• src/index.ts:284-285 (registration)

  Dispatch case in the CallToolRequestSchema handler that routes 'list_directory' calls to the listDirectory method.

  case "list_directory":
    return await this.listDirectory(args.dirpath as string);