Auto Favicon MCP Server

Instructions

Generate a complete favicon set from a PNG image file.

Args:
    image_path: Path to the PNG image file.
    output_path: Directory where favicon files will be generated.
Returns:
    A message describing the generated files and output directory.

Implementation Reference

• src/auto_favicon/server.py:109-149 (handler)

  The primary handler for the 'generate_favicon_from_png' tool, decorated with @mcp.tool() for registration. It validates input paths, reads the PNG image, invokes the helper to generate favicon files, and returns a success message with file list or error.

  @mcp.tool()
  async def generate_favicon_from_png(image_path: str, output_path: str) -> str:
      """
      Generate a complete favicon set from a PNG image file.
  
      Args:
          image_path: Absolute path to the PNG image file.
          output_path: Absolute path to the directory where favicon files will be generated.
      Returns:
          A message describing the generated files and output directory.
      """
      try:
          # Validate absolute paths
          image_path_obj = validate_absolute_path(image_path, "image_path")
          output_path_obj = validate_absolute_path(output_path, "output_path")
          
          # Check if image file exists
          if not image_path_obj.exists():
              return f"Error: Image file does not exist: {image_path}"
          
          if not image_path_obj.is_file():
              return f"Error: Path is not a file: {image_path}"
          
          # Check if output directory can be created
          try:
              output_path_obj.mkdir(parents=True, exist_ok=True)
          except Exception as e:
              return f"Error: Cannot create output directory {output_path}: {str(e)}"
          
          with open(image_path_obj, 'rb') as f:
              image_data = f.read()
          result = create_favicon_set(image_data, str(output_path_obj))
          return (
              f"Successfully generated favicon set!\n\n"
              f"Output directory: {result['output_directory']}\n"
              f"Generated files:\n" + "\n".join(f"- {f}" for f in result['generated_files'])
          )
      except ValueError as e:
          return f"Error: {str(e)}"
      except Exception as e:
          return f"Error generating favicon: {str(e)}"

• src/auto_favicon/server.py:38-107 (helper)

  Key helper function that processes image data to create a full favicon set: PNGs in various sizes, ICO, Apple touch icons, and manifest.json.

  def create_favicon_set(image_data: bytes, output_dir: str) -> Dict[str, Any]:
      """Create a complete favicon set from image data."""
      # Write image data to a temp file
      with tempfile.NamedTemporaryFile(delete=False, suffix='.png') as temp_file:
          temp_file.write(image_data)
          temp_file.flush()
          temp_path = temp_file.name
  
      try:
          with Image.open(temp_path) as img:
              # Convert to RGBA if needed
              if img.mode != 'RGBA':
                  img = img.convert('RGBA')
  
              output_path = Path(output_dir)
              output_path.mkdir(parents=True, exist_ok=True)
              generated_files = []
  
              # Generate PNG favicons
              for size in FAVICON_SIZES:
                  resized = img.resize((size, size), Image.Resampling.LANCZOS)
                  filename = f"favicon-{size}x{size}.png"
                  filepath = output_path / filename
                  resized.save(filepath, "PNG")
                  generated_files.append(str(filepath))
  
              # Generate ICO file
              ico_images = [img.resize((size, size), Image.Resampling.LANCZOS) for size in ICO_SIZES]
              ico_path = output_path / "favicon.ico"
              ico_images[0].save(ico_path, format='ICO', sizes=[(size, size) for size in ICO_SIZES])
              generated_files.append(str(ico_path))
  
              # Generate Apple touch icons
              for size in APPLE_SIZES:
                  resized = img.resize((size, size), Image.Resampling.LANCZOS)
                  filename = f"apple-touch-icon-{size}x{size}.png"
                  filepath = output_path / filename
                  resized.save(filepath, "PNG")
                  generated_files.append(str(filepath))
  
              # Generate manifest.json
              manifest = {
                  "name": "Favicon App",
                  "short_name": "Favicon",
                  "description": "Generated favicon application",
                  "start_url": "/",
                  "display": "standalone",
                  "background_color": "#ffffff",
                  "theme_color": "#000000",
                  "icons": [
                      {
                          "src": f"favicon-{size}x{size}.png",
                          "sizes": f"{size}x{size}",
                          "type": "image/png"
                      } for size in FAVICON_SIZES
                  ]
              }
              manifest_path = output_path / "manifest.json"
              with open(manifest_path, 'w') as f:
                  json.dump(manifest, f, indent=2)
              generated_files.append(str(manifest_path))
  
              return {
                  "generated_files": generated_files,
                  "manifest": manifest,
                  "output_directory": str(output_path)
              }
      finally:
          os.unlink(temp_path)

• src/auto_favicon/server.py:28-36 (helper)

  Helper function used by the handler to validate that input paths are absolute.

  def validate_absolute_path(path: str, path_type: str) -> Path:
      """Validate that a path is absolute and exists (for files) or can be created (for directories)."""
      path_obj = Path(path)
      
      if not path_obj.is_absolute():
          raise ValueError(f"{path_type} must be an absolute path: {path}")
      
      return path_obj

• src/auto_favicon/server.py:21-21 (registration)

  Initialization of the FastMCP server instance where tools are registered via decorators.

  mcp = FastMCP(name="favicon-generator")