BlenderMCP

Instructions

Implementation Reference

• src/blender_mcp/server.py:270-311 (handler)

  The primary handler for the 'get_viewport_screenshot' tool. It uses the @mcp.tool() decorator for automatic registration in FastMCP. The function sends a command to the Blender addon via socket to capture the viewport screenshot, saves it to a temporary PNG file, reads the bytes, cleans up the file, and returns an MCP Image object. The input schema is defined by the function signature (ctx: Context, max_size: int = 800) and docstring.

  @mcp.tool()
  def get_viewport_screenshot(ctx: Context, max_size: int = 800) -> Image:
      """
      Capture a screenshot of the current Blender 3D viewport.
      
      Parameters:
      - max_size: Maximum size in pixels for the largest dimension (default: 800)
      
      Returns the screenshot as an Image.
      """
      try:
          blender = get_blender_connection()
          
          # Create temp file path
          temp_dir = tempfile.gettempdir()
          temp_path = os.path.join(temp_dir, f"blender_screenshot_{os.getpid()}.png")
          
          result = blender.send_command("get_viewport_screenshot", {
              "max_size": max_size,
              "filepath": temp_path,
              "format": "png"
          })
          
          if "error" in result:
              raise Exception(result["error"])
          
          if not os.path.exists(temp_path):
              raise Exception("Screenshot file was not created")
          
          # Read the file
          with open(temp_path, 'rb') as f:
              image_bytes = f.read()
          
          # Delete the temp file
          os.remove(temp_path)
          
          return Image(data=image_bytes, format="png")
          
      except Exception as e:
          logger.error(f"Error capturing screenshot: {str(e)}")
          raise Exception(f"Screenshot failed: {str(e)}")