Geometry Tools

The cad-geometry-mcp server provides mesh geometry operations powered by manifold-3d, a WASM-compiled C++ geometry engine that runs in-process inside Node.js — no Python, no external process.

Engine: manifold-3d WASM

manifold-3d is compiled to WebAssembly and loaded directly into the Node.js worker. This means:

• No subprocess overhead — geometry runs in the same process as the MCP server
• Reliable manifold guarantees — manifold-3d enforces watertight, manifold meshes
• Fast boolean ops — union, difference, intersection at native speed
• No Python dependency — unlike OpenSCAD or FreeCAD integrations

Core Tools

Tool	Description
inspect_mesh	Report vertex count, face count, bounding box, volume, surface area, manifold status
repair_mesh	Fix non-manifold geometry, fill holes, remove degenerate faces
scale_mesh	Scale uniformly or per-axis; optionally fit to max dimension
translate_mesh	Move mesh by X/Y/Z offset
rotate_mesh	Rotate around X, Y, or Z axis by degrees
boolean_mesh	Union, difference, or intersection of two meshes
export_mesh	Write mesh to STL or OBJ

Workflow Tools

Tool	Description
split_mesh	Split a mesh into parts by cutting planes or connected components
add_dowel_connectors	Detect seams between parts and add mating dowel holes/pins
export_parts_as_3mf	Package multiple parts into a single 3MF archive
analyze_printability	Check each part for overhangs, thin walls, minimum feature size

Examples

inspect_mesh

{
  "name": "inspect_mesh",
  "arguments": {
    "input": "/models/ramp.stl"
  }
}

Response:

{
  "vertices": 15420,
  "faces": 30836,
  "bounding_box": {
    "min": [0, 0, 0],
    "max": [320.5, 180.2, 95.0]
  },
  "volume_cm3": 482.3,
  "surface_area_cm2": 1204.7,
  "is_manifold": true
}

scale_mesh

{
  "name": "scale_mesh",
  "arguments": {
    "input": "/models/ramp.stl",
    "output": "/models/ramp_scaled.stl",
    "fit_max_dimension": 256.0
  }
}

Scales the mesh so its longest bounding box dimension equals 256 mm, preserving aspect ratio.

Alternatively, scale per-axis:

{
  "name": "scale_mesh",
  "arguments": {
    "input": "/models/ramp.stl",
    "output": "/models/ramp_scaled.stl",
    "x": 0.5,
    "y": 0.5,
    "z": 0.5
  }
}

split_mesh

{
  "name": "split_mesh",
  "arguments": {
    "input": "/models/ramp_scaled.stl",
    "output_dir": "/models/parts/",
    "cuts": [
      { "axis": "x", "position": 128.0 },
      { "axis": "x", "position": 64.0 }
    ]
  }
}

Produces /models/parts/part_0.stl, part_1.stl, part_2.stl. Each cut is a planar slice perpendicular to the specified axis.

add_dowel_connectors

{
  "name": "add_dowel_connectors",
  "arguments": {
    "parts_dir": "/models/parts/",
    "diameter_mm": 6.0,
    "depth_mm": 10.0,
    "clearance_mm": 0.2,
    "output_dir": "/models/parts_connected/"
  }
}

Detects which faces of adjacent parts share a seam, validates surface contact, and subtracts mating dowel cylinders from each part. See Connector System for details on how seam detection works.