Excel MCP Server

Instructions

Implementation Reference

• src/index.ts:25-28 (schema)

  Zod schema defining the input parameters for the add_worksheet tool: filePath and sheetName.

  const AddWorksheetSchema = z.object({
    filePath: z.string().describe("対象のExcelファイルの絶対パス。既存のファイルである必要があります"),
    sheetName: z.string().describe("作成するワークシート名。英数字、日本語、アンダースコア、ハイフンが使用可能です"),
  });

• src/index.ts:207-228 (handler)

  Core handler function that loads the Excel workbook, checks for existing sheet, adds new worksheet using ExcelJS, saves the file, and returns confirmation.

  async function addWorksheet(filePath: string, sheetName: string): Promise<string> {
    try {
      if (!sheetName || sheetName.trim() === '') {
        throw new Error("ワークシート名が空です");
      }
      
      const workbook = await loadWorkbook(filePath);
      
      // 既存のシート名と重複チェック
      const existingSheet = workbook.getWorksheet(sheetName);
      if (existingSheet) {
        throw new Error(`ワークシート '${sheetName}' は既に存在します`);
      }
      
      workbook.addWorksheet(sheetName);
      await workbook.xlsx.writeFile(filePath);
      
      return `ワークシート '${sheetName}' を追加しました。`;
    } catch (error) {
      throw new McpError(ErrorCode.InternalError, `ワークシート追加エラー: ${error}`);
    }
  }

• src/index.ts:476-480 (registration)

  Tool registration in the listTools handler, defining name, description, and input schema.

  {
    name: "add_worksheet", 
    description: "既存のワークブックにワークシートを追加します",
    inputSchema: zodToJsonSchema(AddWorksheetSchema)
  },

• src/index.ts:535-538 (registration)

  Tool implementation wrapper in the dispatch map, which parses args with schema and delegates to the handler function.

  add_worksheet: async (args: any) => {
    const { filePath, sheetName } = AddWorksheetSchema.parse(args);
    return await addWorksheet(filePath, sheetName);
  },

• src/index.ts:194-204 (helper)

  Helper function to load and validate an Excel workbook, used by the addWorksheet handler.

  async function loadWorkbook(filePath: string): Promise<ExcelJS.Workbook> {
    try {
      validateFilePath(filePath);
      
      const workbook = new ExcelJS.Workbook();
      await workbook.xlsx.readFile(filePath);
      return workbook;
    } catch (error) {
      throw new McpError(ErrorCode.InternalError, `ワークブック読み込みエラー: ${error}`);
    }
  }