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xlwings Excel MCP Server

format_range

Apply formatting to Excel cell ranges including font styles, colors, borders, alignment, and conditional formatting to enhance spreadsheet readability and presentation.

Instructions

Apply formatting to a range of cells.

Args:
    sheet_name: Name of worksheet
    start_cell: Starting cell
    session_id: Session ID from open_workbook (preferred)
    filepath: Path to Excel file (legacy, deprecated)
    end_cell: Ending cell (optional)
    bold: Apply bold formatting
    italic: Apply italic formatting
    underline: Apply underline formatting
    font_size: Font size
    font_color: Font color
    bg_color: Background color
    border_style: Border style
    border_color: Border color
    number_format: Number format
    alignment: Text alignment
    wrap_text: Enable text wrapping
    merge_cells: Merge cells in range
    protection: Cell protection settings (optional)
    conditional_format: Conditional formatting settings (optional)
    
Note: Use session_id for better performance. filepath parameter is deprecated.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
sheet_nameYes
start_cellYes
session_idNo
filepathNo
end_cellNo
boldNo
italicNo
underlineNo
font_sizeNo
font_colorNo
bg_colorNo
border_styleNo
border_colorNo
number_formatNo
alignmentNo
wrap_textNo
merge_cellsNo
protectionNo
conditional_formatNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Implementation Reference

  • MCP tool registration and primary handler for 'format_range'. Dispatches to session-based or legacy filepath-based implementations based on parameters provided.
    @mcp.tool()
    def format_range(
        sheet_name: str,
        start_cell: str,
        session_id: Optional[str] = None,
        filepath: Optional[str] = None,
        end_cell: Optional[str] = None,
        bold: bool = False,
        italic: bool = False,
        underline: bool = False,
        font_size: Optional[int] = None,
        font_color: Optional[str] = None,
        bg_color: Optional[str] = None,
        border_style: Optional[str] = None,
        border_color: Optional[str] = None,
        number_format: Optional[str] = None,
        alignment: Optional[str] = None,
        wrap_text: bool = False,
        merge_cells: bool = False,
        protection: Optional[Dict[str, Any]] = None,
        conditional_format: Optional[Dict[str, Any]] = None
    ) -> str:
        """
        Apply formatting to a range of cells.
        
        Args:
            sheet_name: Name of worksheet
            start_cell: Starting cell
            session_id: Session ID from open_workbook (preferred)
            filepath: Path to Excel file (legacy, deprecated)
            end_cell: Ending cell (optional)
            bold: Apply bold formatting
            italic: Apply italic formatting
            underline: Apply underline formatting
            font_size: Font size
            font_color: Font color
            bg_color: Background color
            border_style: Border style
            border_color: Border color
            number_format: Number format
            alignment: Text alignment
            wrap_text: Enable text wrapping
            merge_cells: Merge cells in range
            protection: Cell protection settings (optional)
            conditional_format: Conditional formatting settings (optional)
            
        Note: Use session_id for better performance. filepath parameter is deprecated.
        """
        try:
            # Support both new (session_id) and old (filepath) API
            if session_id:
                # New API: use session
                session = SESSION_MANAGER.get_session(session_id)
                if not session:
                    return ERROR_TEMPLATES['SESSION_NOT_FOUND'].format(
                        session_id=session_id, 
                        ttl=10  # Default TTL is 10 minutes (600 seconds)
                    )
                
                with session.lock:
                    from xlwings_mcp.xlwings_impl.formatting_xlw import format_range_xlw_with_wb
                    result = format_range_xlw_with_wb(
                        session.workbook,
                        sheet_name=sheet_name,
                        start_cell=start_cell,
                        end_cell=end_cell,
                        bold=bold,
                        italic=italic,
                        underline=underline,
                        font_size=font_size,
                        font_color=font_color,
                        bg_color=bg_color,
                        border_style=border_style,
                        border_color=border_color,
                        number_format=number_format,
                        alignment=alignment,
                        wrap_text=wrap_text,
                        merge_cells=merge_cells
                    )
            elif filepath:
                # Legacy API: backwards compatibility
                logger.warning("Using deprecated filepath parameter. Please use session_id instead.")
                full_path = get_excel_path(filepath)
                from xlwings_mcp.xlwings_impl.formatting_xlw import format_range_xlw
                result = format_range_xlw(
                    filepath=full_path,
                    sheet_name=sheet_name,
                    start_cell=start_cell,
                    end_cell=end_cell,
                    bold=bold,
                    italic=italic,
                    underline=underline,
                    font_size=font_size,
                    font_color=font_color,
                    bg_color=bg_color,
                    border_style=border_style,
                    border_color=border_color,
                    number_format=number_format,
                    alignment=alignment,
                    wrap_text=wrap_text,
                    merge_cells=merge_cells
                )
            else:
                return ERROR_TEMPLATES['PARAMETER_MISSING'].format(
                    param1='session_id',
                    param2='filepath'
                )
            
            return result.get("message", "Range formatted successfully") if "error" not in result else f"Error: {result['error']}"
        except (ValidationError, FormattingError) as e:
            return f"Error: {str(e)}"
        except Exception as e:
            logger.error(f"Error formatting range: {e}")
            raise
  • Core implementation of range formatting using xlwings for legacy filepath mode. Applies font, color, borders, alignment, etc. to specified range.
    def format_range_xlw(
        filepath: str,
        sheet_name: str,
        start_cell: str,
        end_cell: Optional[str] = None,
        bold: bool = False,
        italic: bool = False,
        underline: bool = False,
        font_size: Optional[int] = None,
        font_color: Optional[str] = None,
        bg_color: Optional[str] = None,
        border_style: Optional[str] = None,
        border_color: Optional[str] = None,
        number_format: Optional[str] = None,
        alignment: Optional[str] = None,
        wrap_text: bool = False,
        merge_cells: bool = False
    ) -> Dict[str, Any]:
        """
        Apply formatting to a range of cells using xlwings.
        
        Args:
            filepath: Path to Excel file
            sheet_name: Name of worksheet
            start_cell: Starting cell for formatting
            end_cell: Ending cell for formatting (optional, defaults to start_cell)
            bold: Apply bold formatting
            italic: Apply italic formatting
            underline: Apply underline formatting
            font_size: Font size in points
            font_color: Font color (hex code or color name)
            bg_color: Background color (hex code or color name)
            border_style: Border style (thin, medium, thick, double)
            border_color: Border color (hex code or color name)
            number_format: Number format string (e.g., "0.00", "#,##0", "mm/dd/yyyy")
            alignment: Text alignment (left, center, right, justify)
            wrap_text: Enable text wrapping
            merge_cells: Merge the cell range
            
        Returns:
            Dict with success message or error
        """
        app = None
        wb = None
    
        # Initialize COM for thread safety (Windows)
        _com_initialize()
    
        try:
            logger.info(f"Applying formatting to range {start_cell}:{end_cell or start_cell} in {sheet_name}")
            
            # Check if file exists
            if not os.path.exists(filepath):
                return {"error": f"File not found: {filepath}"}
            
            # Open Excel app and workbook
            app = xw.App(visible=False, add_book=False)
            wb = app.books.open(filepath)
            
            # Check if sheet exists
            sheet_names = [s.name for s in wb.sheets]
            if sheet_name not in sheet_names:
                return {"error": f"Sheet '{sheet_name}' not found"}
            
            sheet = wb.sheets[sheet_name]
            
            # Get the range to format
            if end_cell:
                range_obj = sheet.range(f"{start_cell}:{end_cell}")
            else:
                range_obj = sheet.range(start_cell)
            
            # Apply font formatting
            if bold:
                range_obj.font.bold = True
            if italic:
                range_obj.font.italic = True
            if underline:
                range_obj.font.underline = True
            if font_size:
                range_obj.font.size = font_size
            
            # Apply font color
            if font_color:
                try:
                    rgb = parse_color(font_color)
                    range_obj.font.color = rgb
                    logger.info(f"Applied font color: {font_color} -> RGB{rgb}")
                except ValueError as e:
                    return {"error": str(e)}
            
            # Apply background color
            if bg_color:
                try:
                    rgb = parse_color(bg_color)
                    range_obj.color = rgb
                    logger.info(f"Applied background color: {bg_color} -> RGB{rgb}")
                except ValueError as e:
                    return {"error": str(e)}
            
            # Apply borders using COM API
            if border_style:
                range_com = range_obj.api
                
                # Map border styles to Excel constants
                border_map = {
                    'thin': 1,      # xlThin
                    'medium': -4138, # xlMedium
                    'thick': 4,     # xlThick
                    'double': -4119, # xlDouble
                    'dotted': -4118, # xlDot
                    'dashed': -4115  # xlDash
                }
                
                style_constant = border_map.get(border_style.lower(), 1)
                
                # Apply to all borders
                for border_index in [7, 8, 9, 10]:  # xlEdgeLeft, xlEdgeTop, xlEdgeBottom, xlEdgeRight
                    border = range_com.Borders(border_index)
                    border.LineStyle = style_constant
                    
                    if border_color:
                        try:
                            if border_color.startswith('#'):
                                hex_color = border_color.lstrip('#')
                                rgb_val = int(hex_color[:2], 16) + (int(hex_color[2:4], 16) << 8) + (int(hex_color[4:6], 16) << 16)
                                border.Color = rgb_val
                        except:
                            pass
            
            # Apply number format
            if number_format:
                range_obj.number_format = number_format
            
            # Apply alignment
            if alignment:
                alignment_map = {
                    'left': -4131,    # xlLeft
                    'center': -4108,  # xlCenter
                    'right': -4152,   # xlRight
                    'justify': -4130  # xlJustify
                }
                
                if alignment.lower() in alignment_map:
                    range_obj.api.HorizontalAlignment = alignment_map[alignment.lower()]
            
            # Apply text wrapping
            if wrap_text:
                range_obj.api.WrapText = True
            
            # Merge cells if requested
            if merge_cells:
                range_obj.merge()
            
            # Save the workbook
            wb.save()
            
            logger.info(f"✅ Successfully applied formatting to range")
            return {
                "message": f"Successfully applied formatting to range {start_cell}:{end_cell or start_cell}",
                "range": f"{start_cell}:{end_cell or start_cell}",
                "sheet": sheet_name,
                "formatting_applied": {
                    "bold": bold,
                    "italic": italic,
                    "underline": underline,
                    "font_size": font_size,
                    "font_color": font_color,
                    "bg_color": bg_color,
                    "border_style": border_style,
                    "number_format": number_format,
                    "alignment": alignment,
                    "wrap_text": wrap_text,
                    "merged": merge_cells
                }
            }
            
        except Exception as e:
            logger.error(f"❌ Error applying formatting: {str(e)}")
            return {"error": str(e)}
            
        finally:
            if wb:
                wb.close()
            if app:
                app.quit()
  • Core implementation of range formatting using xlwings for session (workbook object) mode. Identical logic to legacy but takes existing workbook.
    def format_range_xlw_with_wb(
        wb,
        sheet_name: str,
        start_cell: str,
        end_cell: Optional[str] = None,
        bold: bool = False,
        italic: bool = False,
        underline: bool = False,
        font_size: Optional[int] = None,
        font_color: Optional[str] = None,
        bg_color: Optional[str] = None,
        border_style: Optional[str] = None,
        border_color: Optional[str] = None,
        number_format: Optional[str] = None,
        alignment: Optional[str] = None,
        wrap_text: bool = False,
        merge_cells: bool = False
    ) -> Dict[str, Any]:
        """
        Session-based range formatting using existing workbook object.
        
        Args:
            wb: Workbook object from session
            sheet_name: Name of worksheet
            start_cell: Starting cell for formatting
            end_cell: Ending cell for formatting (optional, defaults to start_cell)
            bold: Apply bold formatting
            italic: Apply italic formatting
            underline: Apply underline formatting
            font_size: Font size in points
            font_color: Font color (hex code or color name)
            bg_color: Background color (hex code or color name)
            border_style: Border style (thin, medium, thick, double)
            border_color: Border color (hex code or color name)
            number_format: Number format string (e.g., "0.00", "#,##0", "mm/dd/yyyy")
            alignment: Text alignment (left, center, right, justify)
            wrap_text: Enable text wrapping
            merge_cells: Merge the cell range
            
        Returns:
            Dict with success message or error
        """
        try:
            logger.info(f"🎨 Applying formatting to range {start_cell}:{end_cell or start_cell} in {sheet_name}")
            
            # Check if sheet exists
            sheet_names = [s.name for s in wb.sheets]
            if sheet_name not in sheet_names:
                return {"error": f"Sheet '{sheet_name}' not found"}
            
            sheet = wb.sheets[sheet_name]
            
            # Get the range to format
            if end_cell:
                range_obj = sheet.range(f"{start_cell}:{end_cell}")
            else:
                range_obj = sheet.range(start_cell)
            
            # Apply font formatting
            if bold:
                range_obj.font.bold = True
            if italic:
                range_obj.font.italic = True
            if underline:
                range_obj.font.underline = True
            if font_size:
                range_obj.font.size = font_size
            
            # Apply font color
            if font_color:
                try:
                    rgb = parse_color(font_color)
                    range_obj.font.color = rgb
                    logger.info(f"Applied font color: {font_color} -> RGB{rgb}")
                except ValueError as e:
                    return {"error": str(e)}
            
            # Apply background color
            if bg_color:
                try:
                    rgb = parse_color(bg_color)
                    range_obj.color = rgb
                    logger.info(f"Applied background color: {bg_color} -> RGB{rgb}")
                except ValueError as e:
                    return {"error": str(e)}
            
            # Apply borders using COM API
            if border_style:
                range_com = range_obj.api
                
                # Map border styles to Excel constants
                border_map = {
                    'thin': 1,      # xlThin
                    'medium': -4138, # xlMedium
                    'thick': 4,     # xlThick
                    'double': -4119, # xlDouble
                    'dotted': -4118, # xlDot
                    'dashed': -4115  # xlDash
                }
                
                style_constant = border_map.get(border_style.lower(), 1)
                
                # Apply to all borders
                for border_index in [7, 8, 9, 10]:  # xlEdgeLeft, xlEdgeTop, xlEdgeBottom, xlEdgeRight
                    border = range_com.Borders(border_index)
                    border.LineStyle = style_constant
                    
                    if border_color:
                        try:
                            if border_color.startswith('#'):
                                hex_color = border_color.lstrip('#')
                                rgb_val = int(hex_color[:2], 16) + (int(hex_color[2:4], 16) << 8) + (int(hex_color[4:6], 16) << 16)
                                border.Color = rgb_val
                        except:
                            pass
            
            # Apply number format
            if number_format:
                range_obj.number_format = number_format
            
            # Apply alignment
            if alignment:
                alignment_map = {
                    'left': -4131,    # xlLeft
                    'center': -4108,  # xlCenter
                    'right': -4152,   # xlRight
                    'justify': -4130  # xlJustify
                }
                
                if alignment.lower() in alignment_map:
                    range_obj.api.HorizontalAlignment = alignment_map[alignment.lower()]
            
            # Apply text wrapping
            if wrap_text:
                range_obj.api.WrapText = True
            
            # Merge cells if requested
            if merge_cells:
                range_obj.merge()
            
            # Save the workbook
            wb.save()
            
            logger.info(f"✅ Successfully applied formatting to range")
            return {
                "message": f"Successfully applied formatting to range {start_cell}:{end_cell or start_cell}",
                "range": f"{start_cell}:{end_cell or start_cell}",
                "sheet": sheet_name,
                "formatting_applied": {
                    "bold": bold,
                    "italic": italic,
                    "underline": underline,
                    "font_size": font_size,
                    "font_color": font_color,
                    "bg_color": bg_color,
                    "border_style": border_style,
                    "number_format": number_format,
                    "alignment": alignment,
                    "wrap_text": wrap_text,
                    "merged": merge_cells
                }
            }
            
        except Exception as e:
            logger.error(f"❌ Error applying formatting: {str(e)}")
            return {"error": str(e)}
  • Utility function to parse various color formats (hex, standard names, RGB strings) into RGB tuples used by both format_range handlers.
    def parse_color(color_input: str) -> Tuple[int, int, int]:
        """
        Parse color input to RGB tuple.
        
        Args:
            color_input: Color as hex (#RRGGBB), name (yellow), or RGB string
            
        Returns:
            RGB tuple (r, g, b)
            
        Raises:
            ValueError: If color format is invalid
        """
        if not color_input:
            raise ValueError("Color input is empty")
        
        # Handle hex colors
        if color_input.startswith('#'):
            hex_color = color_input.lstrip('#')
            if len(hex_color) != 6:
                raise ValueError(f"Invalid hex color format: {color_input}. Use #RRGGBB")
            try:
                return tuple(int(hex_color[i:i+2], 16) for i in (0, 2, 4))
            except ValueError:
                raise ValueError(f"Invalid hex color values: {color_input}")
        
        # Handle standard color names
        color_lower = color_input.lower()
        if color_lower in STANDARD_COLORS:
            return STANDARD_COLORS[color_lower]
        
        # Try to parse as RGB tuple string "(r,g,b)"
        if ',' in color_input:
            try:
                # Remove parentheses and spaces
                clean = color_input.strip('() ')
                parts = [int(x.strip()) for x in clean.split(',')]
                if len(parts) == 3 and all(0 <= p <= 255 for p in parts):
                    return tuple(parts)
            except:
                pass
        
        # If nothing worked, provide helpful error
        available_colors = ', '.join(STANDARD_COLORS.keys())
        raise ValueError(
            f"COLOR_FORMAT_ERROR: '{color_input}' is not recognized. "
            f"Use hex format (#RRGGBB) or standard colors: {available_colors}"
        )
  • Input schema and documentation for the format_range tool, defining all parameters, their types, and descriptions.
    """
    Apply formatting to a range of cells.
    
    Args:
        sheet_name: Name of worksheet
        start_cell: Starting cell
        session_id: Session ID from open_workbook (preferred)
        filepath: Path to Excel file (legacy, deprecated)
        end_cell: Ending cell (optional)
        bold: Apply bold formatting
        italic: Apply italic formatting
        underline: Apply underline formatting
        font_size: Font size
        font_color: Font color
        bg_color: Background color
        border_style: Border style
        border_color: Border color
        number_format: Number format
        alignment: Text alignment
        wrap_text: Enable text wrapping
        merge_cells: Merge cells in range
        protection: Cell protection settings (optional)
        conditional_format: Conditional formatting settings (optional)
        
    Note: Use session_id for better performance. filepath parameter is deprecated.
    """
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden for behavioral disclosure. While it mentions performance considerations (session_id preference) and deprecation warnings, it doesn't disclose important behavioral traits: whether this is a destructive operation (overwrites existing formatting), what permissions are needed, error conditions, or how it interacts with other formatting tools. The description is insufficient for a mutation tool with 19 parameters.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description has a clear two-part structure: purpose statement followed by parameter documentation. However, it's quite lengthy due to listing all 19 parameters. While each parameter entry is concise, the overall description could be more efficiently structured, perhaps grouping related formatting parameters. The 'Note' about session_id/filepath is appropriately placed.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (19 parameters, mutation operation) and the presence of an output schema, the description does a reasonable job. The parameter documentation is thorough, but behavioral context is lacking. For a formatting tool that likely modifies workbook state, more information about side effects, error handling, and interaction with other tools would be beneficial despite the output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The description provides a comprehensive list of all 19 parameters with brief explanations, adding significant value beyond the input schema which has 0% description coverage. Each parameter gets a clear label explaining its purpose (e.g., 'bold: Apply bold formatting', 'font_size: Font size'). This effectively compensates for the schema's lack of descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Apply formatting to a range of cells.' This is a specific verb+resource combination that distinguishes it from many siblings like 'apply_formula', 'copy_range', or 'write_data_to_excel'. However, it doesn't explicitly differentiate from 'merge_cells' which is a specific formatting operation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides some usage guidance: 'Use session_id for better performance. filepath parameter is deprecated.' This implies a preference for session_id over filepath, but doesn't explain when to use this tool versus alternatives like 'apply_formula' or 'write_data_to_excel' for different formatting needs. No explicit when-not-to-use guidance is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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