BlenderMCP

Instructions

Implementation Reference

• src/blender_mcp/server.py:527-542 (handler)

  The handler function implementing the get_polyhaven_status tool. It uses @mcp.tool() decorator for registration and schema inference from signature and docstring. Forwards the status check to the Blender connection.
  def get_polyhaven_status(ctx: Context) -> str: """ Check if PolyHaven integration is enabled in Blender. Returns a message indicating whether PolyHaven features are available. """ try: blender = get_blender_connection() result = blender.send_command("get_polyhaven_status") enabled = result.get("enabled", False) message = result.get("message", "") if enabled: message += "PolyHaven is good at Textures, and has a wider variety of textures than Sketchfab." return message except Exception as e: logger.error(f"Error checking PolyHaven status: {str(e)}") return f"Error checking PolyHaven status: {str(e)}"
• src/blender_mcp/server.py:209-241 (helper)

  Helper function get_blender_connection() that internally calls get_polyhaven_status to validate the connection and cache PolyHaven status.
  def get_blender_connection(): """Get or create a persistent Blender connection""" global _blender_connection, _polyhaven_enabled # Add _polyhaven_enabled to globals # If we have an existing connection, check if it's still valid if _blender_connection is not None: try: # First check if PolyHaven is enabled by sending a ping command result = _blender_connection.send_command("get_polyhaven_status") # Store the PolyHaven status globally _polyhaven_enabled = result.get("enabled", False) return _blender_connection except Exception as e: # Connection is dead, close it and create a new one logger.warning(f"Existing connection is no longer valid: {str(e)}") try: _blender_connection.disconnect() except: pass _blender_connection = None # Create a new connection if needed if _blender_connection is None: host = os.getenv("BLENDER_HOST", DEFAULT_HOST) port = int(os.getenv("BLENDER_PORT", DEFAULT_PORT)) _blender_connection = BlenderConnection(host=host, port=port) if not _blender_connection.connect(): logger.error("Failed to connect to Blender") _blender_connection = None raise Exception("Could not connect to Blender. Make sure the Blender addon is running.") logger.info("Created new persistent connection to Blender") return _blender_connection
• src/blender_mcp/server.py:879-943 (helper)

  The asset_creation_strategy prompt instructs to use get_polyhaven_status() as part of asset sourcing strategy.
  @mcp.prompt() def asset_creation_strategy() -> str: """Defines the preferred strategy for creating assets in Blender""" return """When creating 3D content in Blender, always start by checking if integrations are available: 0. Before anything, always check the scene from get_scene_info() 1. First use the following tools to verify if the following integrations are enabled: 1. PolyHaven Use get_polyhaven_status() to verify its status If PolyHaven is enabled: - For objects/models: Use download_polyhaven_asset() with asset_type="models" - For materials/textures: Use download_polyhaven_asset() with asset_type="textures" - For environment lighting: Use download_polyhaven_asset() with asset_type="hdris" 2. Sketchfab Sketchfab is good at Realistic models, and has a wider variety of models than PolyHaven. Use get_sketchfab_status() to verify its status If Sketchfab is enabled: - For objects/models: First search using search_sketchfab_models() with your query - Then download specific models using download_sketchfab_model() with the UID - Note that only downloadable models can be accessed, and API key must be properly configured - Sketchfab has a wider variety of models than PolyHaven, especially for specific subjects 3. Hyper3D(Rodin) Hyper3D Rodin is good at generating 3D models for single item. So don't try to: 1. Generate the whole scene with one shot 2. Generate ground using Hyper3D 3. Generate parts of the items separately and put them together afterwards Use get_hyper3d_status() to verify its status If Hyper3D is enabled: - For objects/models, do the following steps: 1. Create the model generation task - Use generate_hyper3d_model_via_images() if image(s) is/are given - Use generate_hyper3d_model_via_text() if generating 3D asset using text prompt If key type is free_trial and insufficient balance error returned, tell the user that the free trial key can only generated limited models everyday, they can choose to: - Wait for another day and try again - Go to hyper3d.ai to find out how to get their own API key - Go to fal.ai to get their own private API key 2. Poll the status - Use poll_rodin_job_status() to check if the generation task has completed or failed 3. Import the asset - Use import_generated_asset() to import the generated GLB model the asset 4. After importing the asset, ALWAYS check the world_bounding_box of the imported mesh, and adjust the mesh's location and size Adjust the imported mesh's location, scale, rotation, so that the mesh is on the right spot. You can reuse assets previous generated by running python code to duplicate the object, without creating another generation task. 3. Always check the world_bounding_box for each item so that: - Ensure that all objects that should not be clipping are not clipping. - Items have right spatial relationship. 4. Recommended asset source priority: - For specific existing objects: First try Sketchfab, then PolyHaven - For generic objects/furniture: First try PolyHaven, then Sketchfab - For custom or unique items not available in libraries: Use Hyper3D Rodin - For environment lighting: Use PolyHaven HDRIs - For materials/textures: Use PolyHaven textures Only fall back to scripting when: - PolyHaven, Sketchfab, and Hyper3D are all disabled - A simple primitive is explicitly requested - No suitable asset exists in any of the libraries - Hyper3D Rodin failed to generate the desired asset - The task specifically requires a basic material/color """