Blender MCP
Control a running Blender instance from Hermes via socket on TCP port 9876.
Setup (one-time)
1. Install the Blender addon
curl -sL https://raw.githubusercontent.com/ahujasid/blender-mcp/main/addon.py -o ~/Desktop/blender_mcp_addon.py
In Blender: Edit > Preferences > Add-ons > Install > select blender_mcp_addon.py Enable "Interface: Blender MCP"
2. Start the socket server in Blender
Press N in Blender viewport to open sidebar. Find "BlenderMCP" tab and click "Start Server".
3. Verify connection
nc -z -w2 localhost 9876 && echo "OPEN" || echo "CLOSED"
Protocol
Plain UTF-8 JSON over TCP -- no length prefix.
Send: {"type": "", "params": {}} Receive: {"status": "success", "result": } {"status": "error", "message": ""}
Available Commands
| type | params | description |
|---|---|---|
| execute_code | code (str) | Run arbitrary bpy Python code |
| get_scene_info | (none) | List all objects in scene |
| get_object_info | object_name (str) | Details on a specific object |
| get_viewport_screenshot | (none) | Screenshot of current viewport |
Python Helper
Use this inside execute_code tool calls:
import socket, json def blender_exec(code: str, host="localhost", port=9876, timeout=15): s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, port)) s.settimeout(timeout) payload = json.dumps({"type": "execute_code", "params": {"code": code}}) s.sendall(payload.encode("utf-8")) buf = b"" while True: try: chunk = s.recv(4096) if not chunk: break buf += chunk try: json.loads(buf.decode("utf-8")) break except json.JSONDecodeError: continue except socket.timeout: break s.close() return json.loads(buf.decode("utf-8"))
Common bpy Patterns
Clear scene
bpy.ops.object.select_all(action='SELECT') bpy.ops.object.delete()
Add mesh objects
bpy.ops.mesh.primitive_uv_sphere_add(radius=1, location=(0, 0, 0)) bpy.ops.mesh.primitive_cube_add(size=2, location=(3, 0, 0)) bpy.ops.mesh.primitive_cylinder_add(radius=0.5, depth=2, location=(-3, 0, 0))
Create and assign material
mat = bpy.data.materials.new(name="MyMat") mat.use_nodes = True bsdf = mat.node_tree.nodes.get("Principled BSDF") bsdf.inputs["Base Color"].default_value = (R, G, B, 1.0) bsdf.inputs["Roughness"].default_value = 0.3 bsdf.inputs["Metallic"].default_value = 0.0 obj.data.materials.append(mat)
Keyframe animation
obj.location = (0, 0, 0) obj.keyframe_insert(data_path="location", frame=1) obj.location = (0, 0, 3) obj.keyframe_insert(data_path="location", frame=60)
Render to file
bpy.context.scene.render.filepath = "/tmp/render.png" bpy.context.scene.render.engine = 'CYCLES' bpy.ops.render.render(write_still=True)
Pitfalls
- Must check socket is open before running (nc -z localhost 9876)
- Addon server must be started inside Blender each session (N-panel > BlenderMCP > Connect)
- Break complex scenes into multiple smaller execute_code calls to avoid timeouts
- Render output path must be absolute (/tmp/...) not relative
- shade_smooth() requires object to be selected and in object mode
