MCP PDF Forms

Instructions

Generate an image with the specified form field highlighted with a red box

Args:
    pdf_path: Path to the PDF file
    field_name: Name of the form field to highlight

Returns:
    Image of the page with the field highlighted

Implementation Reference

• mcp_pdf_forms/server.py:133-202 (handler)

  The main handler function for the 'highlight_form_field' tool. It opens the PDF using PyMuPDF, locates the specified form field on its page, renders the page at 2x zoom, draws a thick red rectangle around the field using PIL, and returns the resulting PNG image via MCP's Image type. The @mcp.tool() decorator registers it as a tool.

  @mcp.tool()
  def highlight_form_field(pdf_path: str, field_name: str) -> Image:
      """
      Generate an image with the specified form field highlighted with a red box
  
      Args:
          pdf_path: Path to the PDF file
          field_name: Name of the form field to highlight
  
      Returns:
          Image of the page with the field highlighted
      """
      try:
          doc = fitz.open(pdf_path)
  
          # Find the field and its page
          field_found = False
          field_page = None
          field_rect = None
  
          for page_num, page in enumerate(doc):
              for widget in page.widgets():
                  if widget.field_name == field_name:
                      field_found = True
                      field_page = page
                      field_rect = widget.rect
                      break
              if field_found:
                  break
  
          if not field_found:
              raise ValueError(f"Field '{field_name}' not found in the document")
  
          # Render the page as an image
          zoom = 2  # higher zoom for better quality
          mat = fitz.Matrix(zoom, zoom)
          pix = field_page.get_pixmap(matrix=mat)
  
          # Convert to PIL Image
          img = PILImage.frombytes("RGB", [pix.width, pix.height], pix.samples)
  
          # Draw red rectangle around the form field
          draw = ImageDraw.Draw(img)
  
          # Scale rectangle coordinates according to zoom factor
          rect = (
              field_rect.x0 * zoom,
              field_rect.y0 * zoom,
              field_rect.x1 * zoom,
              field_rect.y1 * zoom,
          )
  
          # Draw rectangle with 3-pixel width
          for i in range(3):
              draw.rectangle(
                  (rect[0] - i, rect[1] - i, rect[2] + i, rect[3] + i), outline="red"
              )
  
          # Convert to bytes
          buffer = io.BytesIO()
          img.save(buffer, format="PNG")
          img_bytes = buffer.getvalue()
  
          doc.close()
  
          # Return MCP Image object
          return Image(data=img_bytes, format="png")
      except Exception as e:
          raise Exception(f"Error highlighting form field: {str(e)}")