Blender Mcp — Control Blender directly from Hermes via socket connection to the blender-mcp addon

Blender Mcp

Control Blender directly from Hermes via socket connection to the blender-mcp addon. Create 3D objects, materials, animations, and run arbitrary Blender Python (bpy) code. Use when user wants to create or modify anything in Blender.

Skill metadata

Source	Optional — install with hermes skills install official/creative/blender-mcp
Path	optional-skills/creative/blender-mcp
Version	1.0.0
Author	alireza78a

Reference: full SKILL.md

The following is the complete skill definition that Hermes loads when this skill is triggered. This is what the agent sees as instructions when the skill is active.

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”: “<command>”, “params”: {<kwargs>}} Receive: {“status”: “success”, “result”: <value>} {“status”: “error”, “message”: “<reason>“}

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