RhinoMCP: an MCP Server for Rhino 3D

105 tools for AI-driven 3D modeling, analysis, diagnostics, and Grasshopper integration via the Model Context Protocol.

RhinoMCP connects Claude to Rhino 3D through a comprehensive set of tools covering everything from basic primitives to advanced surface modeling (loft, sweep, revolve), boolean operations, mesh diagnostics, block management, and parametric design with Grasshopper.

Architecture

┌────────────────┐   stdio    ┌──────────────┐   TCP/JSON    ┌──────────────┐
│ Claude Desktop │◄──────────►│  rhino_mcp   │◄─────────────►│    Rhino 3D  │
│                │   (MCP)    │  (Python)    │  localhost:   │  listener.py │
│                │            │  server.py   │    9876       │  (inside     │
└────────────────┘            └──────────────┘               │   Rhino)     │
                                                             └──────────────┘

MCP Server (rhino_mcp/). Python package using FastMCP. Communicates with Claude via stdio and with Rhino via TCP.

Rhino Listener (rhino/listener.py). Python script that runs inside Rhino. Opens a TCP server, receives JSON commands, executes them using RhinoCommon/rhinoscriptsyntax, and returns results.

Capabilities

Geometry Creation (21 tools)

Tool	Description
create_point, create_points	Single or batch point creation
create_line, create_polyline	Lines and polylines
create_curve	Interpolated NURBS curves
create_circle, create_arc, create_ellipse	Circular geometry
create_rectangle	Rectangular polylines
create_sphere, create_box, create_cylinder, create_cone, create_torus	Solid primitives
create_extrusion, create_pipe	Extrude and pipe along curves
create_surface_from_points, create_mesh	NURBS surfaces and meshes
create_text	Text dots
create_loft	Loft surfaces through cross-sections
create_sweep1, create_sweep2	Single and two-rail sweeps
create_revolve	Revolve profiles around an axis
create_planar_surface, create_patch	Planar and patch surfaces

Transforms (8 tools)

move, rotate, scale, scale_non_uniform, mirror, copy, array_linear, array_polar

Boolean Operations (3 tools)

boolean_union, boolean_difference, boolean_intersection

Modification (18 tools)

Tool	Description
delete, set_color, set_material, set_name, set_layer	Basic modifications
group, ungroup	Grouping
join, explode	Join and explode geometry
trim, split	Trim and split curves
offset_curve, offset_surface	Offset geometry
fillet_edge, chamfer_edge, fillet_curves	Edge treatments
cap_planar_holes	Cap open breps
extend_curve, rebuild_curve	Curve editing
project_to_surface	Project curves onto surfaces
duplicate_edge, duplicate_border	Extract edges/borders

Blocks & Instances (4 tools)

create_block, insert_block, list_blocks, explode_block

User Data (2 tools)

set_user_text, get_user_text: store metadata, BIM data, costs, etc.

Layers (6 tools)

list_layers, create_layer, delete_layer, set_layer_color, set_layer_visibility, set_current_layer

Materials (3 tools)

list_materials, create_material, assign_material

Analysis (10 tools)

Tool	Description
get_bounding_box, get_area, get_volume, get_length	Measurements
distance, closest_point	Spatial queries
intersect	Find intersections between objects
get_curvature	Curvature analysis
is_point_on_surface, is_point_in_solid	Point containment tests

Diagnostics (4 tools)

Tool	Description
check_objects	Check validity, find bad geometry
get_naked_edges	Find gaps in surfaces
check_mesh	Mesh quality analysis
repair_mesh	Fix mesh issues automatically

View (5 tools)

zoom_extents, set_view, capture_view (with base64 option), list_views, set_display_mode

Grasshopper (3 tools)

gh_run_script, gh_set_slider, gh_get_outputs

Code Execution (2 tools)

run_python, run_command: full access to rhinoscriptsyntax and RhinoCommon

Undo/Redo (2 tools)

undo, redo

Scene (4 tools)

scene_info, get_objects, get_object (detailed with edge info), select_objects

Import/Export (2 tools)

export (.3dm, .obj, .stl, .step, .iges, .fbx), import_file

Bold = new in v2.0

Prerequisites

• Rhino 7 or 8 (Windows or Mac)
• Python 3.10+
• uv package manager (install)

Installation

1. Clone and install

git clone https://github.com/kbangaru-cyber/rhino-mcp.git
cd Rhino_MCP
uv sync

2. Start the Rhino listener

In Rhino:

1. Go to Tools > PythonScript > Run
2. Select rhino/listener.py
3. You should see:

============================================================
  RhinoMCP Listener v2.0.0
  Listening on 127.0.0.1:9876
  Registered handlers: 90
  Ready for MCP connection (Claude)
============================================================

3. Configure Claude Desktop

Claude Desktop

Edit claude_desktop_config.json:

{
  "mcpServers": {
    "rhino": {
      "command": "uv",
      "args": ["--directory", "/ABSOLUTE/PATH/TO/Rhino_MCP", "run", "rhino-mcp"],
      "env": {
        "RHINO_MCP_HOST": "127.0.0.1",
        "RHINO_MCP_PORT": "9876",
        "RHINO_MCP_TIMEOUT": "30"
      }
    }
  }
}

Usage Examples

Create a simple building form

"Create a 10x8x4 meter box for the building volume, then add a cylinder of radius 2 and height 6 at the center for a tower. Union them together and fillet all edges with radius 0.3."

Diagnose model problems

"Check all objects in the scene for problems. Find any naked edges and tell me what needs fixing."

Parametric design

"Create a vase shape by making a profile curve and revolving it. Then create a polar array of decorative cylinders around it."

Built-in Prompts

RhinoMCP includes guided workflow prompts:

• model-from-description: structured workflow for creating 3D models from text descriptions
• diagnose-model: systematic approach to finding and fixing model problems
• parametric-design: guide for Grasshopper/parametric workflows

Resources

The server exposes live data as MCP resources:

URI	Description
rhino://scene/info	Current scene overview
rhino://layers	Layer tree
rhino://materials	Material list
rhino://blocks	Block definitions

Configuration

Environment Variable	Default	Description
RHINO_MCP_HOST	127.0.0.1	Rhino listener host
RHINO_MCP_PORT	9876	Rhino listener port
RHINO_MCP_TIMEOUT	30	Command timeout (seconds)

Development

# Install dev dependencies
uv sync --extra dev

# Run tests (no Rhino needed)
uv run pytest -v

# Lint
uv run ruff check .

# Type check
uv run mypy rhino_mcp

Integration testing

With Rhino running and the listener active:

uv run pytest -v -m integration

Protocol

Commands are JSON objects sent over TCP (newline-delimited):

{"id": "abc123", "action": "create_sphere", "params": {"center": [0,0,0], "radius": 5}}

Responses:

{"id": "abc123", "ok": true, "result": {"guid": "d3e4f5..."}}

Thread Safety

The Rhino listener uses Rhino.RhinoApp.InvokeOnUiThread() on Rhino 8+ to ensure all geometry operations run on the UI thread. On Rhino 7, operations execute directly (which is safe for single-client connections).

License

MIT. See LICENSE.

Author

Karthick Raja B G, portfolio · GitHub

Related work: SPIDER, a Grasshopper plugin for computational geometry and spatial analysis.