Feature Request: Add `excel_create_file` tool to create new Excel files

[vielhuber]

Problem

excel_write_to_sheet fails with the following error when the target file does not exist yet:

Error calling tool 'excel_write_to_sheet': zip: not a valid zip file

Root Cause

writeSheet() in internal/tools/excel_write_to_sheet.go always opens an existing file first:

// excel_write_to_sheet.go:101
workbook, closeFn, err := excel.OpenFile(fileAbsolutePath)
if err != nil {
    return nil, err  // <-- error is thrown here when file doesn't exist
}

excel.OpenFile internally calls excelize.OpenFile(absoluteFilePath), which requires a valid .xlsx ZIP archive to already exist on disk. If the file is missing, excelize returns zip: not a valid zip file.

The newSheet: true parameter of excel_write_to_sheet only creates a new sheet within an existing workbook — it does not create a new file.

There is no Excel.CreateNewFile() method in the Excel interface (internal/excel/excel.go), and no corresponding tool exposed via MCP.

Expected Behavior

It should be possible to create a new .xlsx file from scratch via an MCP tool call, without requiring the file to pre-exist on disk.

Proposed Solution

Add a new tool excel_create_file that creates an empty Excel workbook at a given path:

Tool definition:

• fileAbsolutePath (required) — Absolute path where the new .xlsx file should be created
• sheetName (optional, default: "Sheet1") — Name of the initial worksheet

Implementation sketch:

// internal/tools/excel_create_file.go

func createFile(fileAbsolutePath string, sheetName string) (*mcp.CallToolResult, error) {
    f := excelize.NewFile()
    defer f.Close()

    if sheetName != "Sheet1" {
        f.SetSheetName("Sheet1", sheetName)
    }

    file, err := os.OpenFile(filepath.Clean(fileAbsolutePath), os.O_WRONLY|os.O_TRUNC|os.O_CREATE, os.ModePerm)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    if err := f.Write(file); err != nil {
        return nil, err
    }

    result := "# Notice\n"
    result += fmt.Sprintf("File [%s] created with sheet [%s].\n", fileAbsolutePath, sheetName)
    return mcp.NewToolResultText(result), nil
}

Alternatively, excel_write_to_sheet with newSheet: true could be extended to automatically create the file if it does not exist yet, which would be a non-breaking improvement to the existing API.

Workaround

Until this is implemented, a new file can be created via an external tool (e.g. a Shell MCP) using Python:

python3 -c "import openpyxl; wb = openpyxl.Workbook(); wb.save('/path/to/file.xlsx')"

Environment

• @negokaz/excel-mcp-server (latest via npx)
• Linux (no OLE/Windows backend available, using excelize backend)