Content
# SolidWorks MCP
[](https://pypi.org/project/solidworks-mcp/)
[](https://github.com/hjbaard/SolidWorks-MCP/blob/main/LICENSE)
Let an AI agent (Claude, or any other MCP client) model real parametric parts and
assemblies in **your own SolidWorks** — and **check its own work**. Every
modelling call returns the measured volume, mass and bounding box, so the agent
can compare the result with the spec and correct itself instead of guessing that
it "looks about right".
<!-- mcp-name: io.github.hjbaard/solidworks-mcp -->
<p align="center">
<img src="https://raw.githubusercontent.com/hjbaard/SolidWorks-MCP/main/Docs/images/bracket.png" width="32%" alt="3D-print mounting bracket with counterbored holes, bolt circle and cable slot">
<img src="https://raw.githubusercontent.com/hjbaard/SolidWorks-MCP/main/Docs/images/thread.png" width="32%" alt="M10 bolt with a real, printable ISO metric thread">
<img src="https://raw.githubusercontent.com/hjbaard/SolidWorks-MCP/main/Docs/images/vase.png" width="32%" alt="Revolved and shelled vase">
</p>
<p align="center">
<img src="https://raw.githubusercontent.com/hjbaard/SolidWorks-MCP/main/Docs/images/pipe.png" width="32%" alt="Swept pipe with rounded bends">
<img src="https://raw.githubusercontent.com/hjbaard/SolidWorks-MCP/main/Docs/images/loft.png" width="32%" alt="Lofted and shelled horn">
</p>
<p align="center"><sub>Built by the tools themselves: a mounting bracket (every step checked against a hand calculation), an M10 bolt with a real thread, a revolved + shelled vase, a swept pipe, a lofted + shelled horn.</sub></p>
## Why this server
- **It verifies, not just generates.** Features report measured geometry;
dimensions and mates are measured back after the rebuild.
- **Fully defined sketches.** Every sketch is constrained the way a designer
would: dimensions from the origin, relations only where the geometry is
exactly horizontal, vertical or on the origin. Tools return their dimensions
by role (`width@Sketch1`), so the part stays editable, in SolidWorks or
through the agent.
- **Real CAD, not just primitives.** Extrude, revolve, sweep, loft and splines;
holes, counterbores, slots and pockets on any face; rounded polygon corners; ISO holes from the Hole Wizard; real ISO metric threads;
fillets, chamfers, shells, patterns, mirrors, ribs, equations and materials. Assemblies
with mates and interference checks. STEP/STL/3MF export and screenshots.
Engraved and embossed text. Work on existing parts: list, delete and suppress features; read, extrude and cut a person's sketches; import STEP. Joints with concentric and angle mates, checked over their range. Printability checks and dimensioned drawings. 68 tools in total.
- **It fails loud.** A call that cannot do what was asked returns
`{ok: false, error}` with the cause, never silently wrong geometry.
- **A fixed, typed tool surface.** There is no "run arbitrary code" tool; the
agent can only do what the tools allow.
- **Tested against real SolidWorks.** 465 tests; each feature's integration test
compares the result with a hand calculation.
- **Local.** It talks to your running SolidWorks over COM; the server itself
makes no network calls.
## Quickstart
1. Install [uv](https://docs.astral.sh/uv/getting-started/installation/).
2. **Start SolidWorks** and leave it open (the server attaches to the running
instance — it does not launch one).
3. Register the server with your MCP client.
**Claude Code:**
```bash
claude mcp add solidworks -- uvx solidworks-mcp
```
**Claude Desktop** (`claude_desktop_config.json`) or any other client:
```json
{
"mcpServers": {
"solidworks": {
"command": "uvx",
"args": ["solidworks-mcp"]
}
}
}
```
It is also listed in the official
[MCP Registry](https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.hjbaard/solidworks-mcp)
as `io.github.hjbaard/solidworks-mcp`.
4. Ask for a part, for example:
> Design a 100 × 80 × 8 mm mounting plate with a Ø16 mm centre bore, four
> counterbored M5 holes 12 mm from the corners and R5 corners. Check the
> volume against your own calculation, then export a fine STL.
## Guidelines for agents
The server hands every MCP client short modelling guidelines when it connects
(conventions, verify each step, known pitfalls). The full guide is the resource
`solidworks://guide`: recipes for holes, ribs, threads and assemblies, 3D-print
advice, and how to reverse-engineer a part from a mesh (STL/3MF). The same text
is in [`src/solidworks_mcp/guide.md`](https://github.com/hjbaard/SolidWorks-MCP/blob/main/src/solidworks_mcp/guide.md).
## Requirements and compatibility
- Windows, with SolidWorks installed, licensed and **running**.
- Python 3.11+ (uv fetches one if needed).
- **Tested on SOLIDWORKS 2026** (3DEXPERIENCE R2026x). The API calls it uses
exist since SOLIDWORKS 2020 SP2, so 2020–2025 should work, but that is
**untested**. To check your installation, run this with SolidWorks open:
```bash
uvx solidworks-mcp --selftest
```
It builds a few small parts, compares each with a hand calculation and
closes them unsaved. Please paste its output in a
[compatibility report](https://github.com/hjbaard/SolidWorks-MCP/issues/new?template=compatibility.yml),
whether it worked or not.
**Status: early (0.x).** It works end-to-end, but tool names and conventions
may still change. See [CHANGELOG.md](https://github.com/hjbaard/SolidWorks-MCP/blob/main/CHANGELOG.md).
## Troubleshooting
- **Start with the selftest**: `uvx solidworks-mcp --selftest` shows your
SolidWorks release, language and templates, and which tool areas work. Add
its output to a [bug report](https://github.com/hjbaard/SolidWorks-MCP/issues/new?template=bug_report.yml).
- **"No running SolidWorks found" / connection fails** — SolidWorks must be
*running* before you start the server or run a script; it attaches to the active
instance via `GetActiveObject` and does not launch one.
- **First call is slow or `EnsureModule` errors** — the first COM call generates the
makepy typelib wrappers under your temp `gen_py` folder. Let it finish; if it gets
into a bad state, delete the `gen_py` cache and retry. Early binding is mandatory on
this build (see [Architecture](#architecture)).
- **A feature returns `{ok: false, error: ...}`** — that is by design: every tool
fails loud with a readable message rather than silently producing wrong
geometry. Read the message; it names the likely cause.
- **Only tested against SOLIDWORKS 2026 (3DEXPERIENCE R2026x).** On other builds the
verified enum values or method signatures may differ — re-run
`scripts/introspect_api.py` to inspect your installed typelib.
## Development
Clone the repository, then install it editable into a venv:
```powershell
python -m venv .venv
.\.venv\Scripts\python.exe -m pip install -e .[dev]
```
To run the MCP server from this checkout instead of via uvx, point your client
at the venv's Python:
```json
{
"mcpServers": {
"solidworks": {
"command": "C:\\path\\to\\SolidWorks-MCP\\.venv\\Scripts\\python.exe",
"args": ["-m", "solidworks_mcp.server"]
}
}
}
```
### Run the verification scripts
With SolidWorks open:
```powershell
.\.venv\Scripts\python.exe scripts\probe_connection.py # M0
.\.venv\Scripts\python.exe scripts\m1_block.py # M1
.\.venv\Scripts\python.exe scripts\m2_parametric.py # M2
.\.venv\Scripts\python.exe scripts\test_mcp_server.py # M3 (full MCP loop over stdio)
.\.venv\Scripts\python.exe scripts\m5_demo_bracket.py # M5 (3D-print bracket, every step verified)
```
`scripts/introspect_api.py` regenerates/inspects the installed typelib and prints
verified enum values — run it if SolidWorks is upgraded and signatures change.
### Tests
```powershell
.\.venv\Scripts\python.exe -m pytest # all tests
.\.venv\Scripts\python.exe -m pytest -m "not solidworks" # fast unit layer, no SolidWorks
```
Two layers: **pure unit tests** (units, selector/direction parsing, polygon
cleaning, the component-placement maths, and that every MCP tool forwards its
arguments to the right session method) run anywhere; **integration tests**
(`solidworks` marker) drive a running SolidWorks and verify each feature's
volume — or each component's placement — against a hand calc. They auto-skip if
SolidWorks isn't reachable.
## Tools
The server speaks MCP over **stdio**.
### Part tools
| Tool | Purpose |
|---|---|
| `get_status` | Is SolidWorks reachable? revision, server version, active/current part |
| `new_part` | Create a new empty part (becomes current) |
| `add_box(width_mm, height_mm, depth_mm, name)` | Sketch rectangle + extrude; returns mass properties |
| `add_cylinder(diameter_mm, height_mm, name)` | Cylinder by revolving a profile 360° about an axis (Y axis) |
| `add_disc(diameter_mm, thickness_mm, name, x_mm, y_mm)` | Disc/puck/flange: circle extruded along +Z, centred at (x, y) (holes/patterns compose) |
| `add_cone(bottom_diameter_mm, top_diameter_mm, height_mm, name)` | Cone/frustum by revolve (top Ø = 0 → full cone) |
| `add_revolved_profile(profile_mm, angle_deg, name, corner_radii_mm)` | Revolve any closed `(radius, height)` profile about the axis (shafts, vases, rings); `corner_radii_mm` rounds its edges |
| `add_swept_pipe(path_mm, diameter_mm, bend_radius_mm, name)` | Sweep a round profile along a 2D path with rounded bends (pipes, tubes, rods) |
| `add_swept_profile(profile_mm, path_mm, bend_radius_mm, name, corner_radii_mm)` | Sweep any closed cross-section along a 2D path (rails, gaskets, trim, channels); `corner_radii_mm` rounds the cross-section |
| `add_lofted_solid(profiles_mm, heights_mm, name)` | Loft/blend 2+ polygon profiles on stacked parallel planes (transitions, adapters) |
| `add_rib(start_mm, end_mm, toward_mm, thickness_mm, z_mm, name)` | Straight rib / gusset in a plane parallel to Front at `z_mm`, grown toward `toward_mm` until it meets the part (L-bracket gussets) |
| `add_extruded_profile(points_mm, depth_mm, name, corner_radii_mm)` | Extrude any closed polygon `[[x,y],…]` (brackets, sections); `corner_radii_mm` rounds its corners with real sketch fillets, each radius a dimension |
| `add_extruded_spline(points_mm, depth_mm, name)` | Extrude a smooth closed spline through points (free-form/organic outlines) |
| `add_hole(diameter_mm, x_mm, y_mm, name)` | Cut a circular through-hole at (x, y) through the depth axis |
| `add_counterbore_hole(clearance_diameter_mm, cbore_diameter_mm, cbore_depth_mm, x_mm, y_mm, name)` | Counterbored screw hole (flush cap-head / heat-set insert) on +Z |
| `add_thread(size, x_mm, y_mm, z_mm, length_mm, internal, name)` | Real, printable ISO metric thread (e.g. `M10x1.5`) from a rod's end edge or a hole's mouth, via SolidWorks' Thread feature; the size is checked against the thread profiles. Internal: drill the basic minor diameter first (M10x1.5 → Ø8.376) |
| `add_hole_on_face(diameter_mm, face, x_mm, y_mm, z_mm, depth_mm, name)` | Round hole on ANY planar face at a 3D point, through or blind (side holes, heat-set insert holes); the face through the point is used |
| `add_hole_wizard(kind, size, face, x_mm, y_mm, z_mm, depth_mm, fit, thread, name)` | ISO hole from SolidWorks' Hole Wizard tables: clearance (ISO 273 fits), counterbore, countersink or tapped; `thread="modeled"` cuts a real, printable thread |
| `add_boss_on_face(diameter_mm, face, x_mm, y_mm, z_mm, height_mm, name)` | Round boss (standoff, peg) grown out of ANY planar face |
| `add_extruded_profile_on_face(points_mm, face, depth_mm, name, corner_radii_mm)` | Polygon pad/ledge grown out of ANY planar face (3D points on the face) |
| `add_text_on_face(text, face, x_mm, y_mm, z_mm, height_mm, depth_mm, emboss, font, name)` | Engrave text into ANY planar face, or emboss it: labels, version numbers; the position is two dimensions |
| `cut_profile(points_mm, depth_mm, name, corner_radii_mm)` | Cut a polygon pocket/slot from the +Z face (blind or through) |
| `cut_profile_on_face(points_mm, face, depth_mm, name, corner_radii_mm)` | Cut a polygon pocket on ANY face (3D points on the face) |
| `cut_profile_through_plane(points_mm, plane, depth_mm, name, corner_radii_mm)` | Cut a polygon drawn on the Front/Top/Right plane or a plane by name, through all both ways or `depth_mm` centred on the plane (wedges, side windows, symmetric recesses); `keep_inside` keeps the profile instead, so two views make a 3D shape |
| `cut_offset_pocket(face, x_mm, y_mm, z_mm, rim_mm, depth_mm, name)` | Pocket a face leaving a rim along its outline (I-beam web, tray, frame); rim and depth are dimensions |
| `cut_slot(length_mm, width_mm, x_mm, y_mm, angle_deg, depth_mm, name)` | Cut a straight slotted hole (obround) on the +Z face at any angle |
| `add_extruded_slot(start_mm, end_mm, width_mm, depth_mm, name)` | Extrude a stadium (rounded tab, lug, link) between two points, the round ends centred on them |
| `add_fillet(radius_mm, edges, name)` | Round edges (`edges`: `all`, axis `x`/`y`/`z`, a face outline `"+z:outline"`, or indices `"2,5"`) |
| `add_chamfer(distance_mm, edges, name)` | Chamfer edges at 45° (`edges`: `all`, axis, a face outline, or indices) |
| `add_shell(thickness_mm, open_face)` | Hollow to a wall thickness; open a face (`+z`/…) or `none` |
| `add_linear_pattern(count, spacing_mm, direction, feature_name)` | Repeat a feature N times along `+x`/`-x`/… |
| `add_circular_pattern(count, center_x_mm, center_y_mm, feature_name)` | Repeat a feature N times around an axis (bolt circle) |
| `add_mirror(plane, offset_mm, features, name)` | Mirror features (copies follow their seeds) or the whole body about the Front/Top/Right plane, or a plane by name, moved `offset_mm`; fails when a copy would land outside the part |
| `set_dimension(dimension_name, value_mm)` | Change a named driving dim (e.g. `D1@BlockExtrude`, or any name a tool returned in `dimensions`), rebuild, remeasure; an angle in degrees |
| `set_equation(equation)` | Add a global equation or variable linking dims (e.g. `"W" = 40`, then `"width@Sketch1" = "W"`) |
| `slice_mesh(path, axis, heights_mm, frame)` | Cross-sections of an STL/3MF mesh as polygon loops, ready to use as profiles |
| `compare_with_mesh(path, axis, heights_mm, frame, offset_mm)` | Compare the part's cross-sections with a reference mesh (area and extent differences) |
| `read_sketch(name)` | A sketch read back in model coordinates: lines, arcs, circles, splines, its dimensions, fully defined or not |
| `extrude_sketch(sketch, depth_mm, reverse, name)` / `cut_sketch(sketch, depth_mm, reverse, name)` | Build on an existing sketch by name (one a person drew): extrude it, or cut it blind or through all |
| `list_dimensions()` | Every dimension in the part: name (for `set_dimension`), feature, value, unit |
| `list_features()` | The part's history in tree order (name, type, suppressed); flags features that fail to rebuild and sketches that are not fully defined |
| `delete_feature(name, with_children)` | Undo a step: delete a feature with its sketch; refuses (and names them) while other features depend on it, unless `with_children` |
| `suppress_feature(name, suppress)` | Take a feature out but keep it and its dimensions (try a variant); `suppress=False` brings it back with its dependents |
| `set_material(name, database)` | Assign a material (e.g. `6061 Alloy`) so mass/density are real |
| `rebuild(top_only)` | Force rebuild, report errors |
| `get_mass_properties` | Volume, mass, density, surface area, centre of mass, bounding box |
| `get_bounding_box` | Tight part bounding box (min/max/size, mm) |
| `list_faces(component)` / `list_edges` | Inspect faces (normal/area/centre; a cylinder's axis, radius and centre, also of a component in an assembly) and edges (type/axis/length) by index |
| `check_printability(up, overhang_deg, min_wall_mm)` | For a print direction: overhanging faces (area, worst lean, centre), bed contact, height; with `min_wall_mm` the walls thinner than that |
| `export(path, file_format, quality, deviation_mm, angle_deg)` | STEP/STL/IGES/Parasolid/3MF (silent; verifies file). STL/3MF tessellation: `quality` `coarse`/`fine`, or explicit `deviation_mm`+`angle_deg` |
| `screenshot(path, view, zoom_mm)` | PNG/BMP/JPG from a standard view (`iso`, `front`, `top`, …), zoomed to fit or onto a region |
| `make_drawing(path)` | 2D drawing as PDF or editable `.slddrw`: front, top, right (first angle) and isometric views on A4 with the model's own dimensions, each once |
| `save_part(path)` / `open_part(path)` | Save to / open a native `.sldprt`; `open_part` also imports STEP, IGES and Parasolid files as a part to build on |
| `close_part(save)` | Close the current part or assembly; without one, SolidWorks' active document if it is saved |
### Assembly tools
| Tool | Purpose |
|---|---|
| `new_assembly` | Create a new empty assembly (becomes the current document) |
| `open_assembly(path)` / `save_assembly(path)` | Open / save a native `.sldasm`; `open_assembly` also imports STEP, IGES and Parasolid assemblies, parts as components in place |
| `insert_component(path, x_mm, y_mm, z_mm, fixed)` | Insert a part with its **origin** at (x, y, z); the first component is fixed by default |
| `list_components` | Name, path, fixed, position, rotation and bounding box of every component (its own extent, also when turned), and the mates with their dimensions and errors |
| `set_component_transform(name, x_mm, y_mm, z_mm, rx_deg, ry_deg, rz_deg)` | Move/rotate a component; the transform is read back and verified |
| `add_mate(comp_a, face_a, comp_b, face_b, mate_type, distance_mm, angle_deg, flip)` | Mate two faces (by direction, or `#index` from `list_faces`): `coincident`, `distance`, `parallel`, `perpendicular`, `angle`, or `concentric` between cylinders — measured back afterwards; a refused mate is removed. A distance or angle mate returns its dimension: a joint angle as one number |
| `check_motion(dimension_name, values, distances)` | Step a joint through its range: overlapping pairs and chosen distances per step, the smallest distance and where it occurs |
| `check_interference` | Component pairs whose solids overlap, with the volume in mm³ (touching faces don't count) |
| `measure_distance(component_a, component_b, point_mm)` | Smallest distance between two components, or to a point (with the nearest point, and whether the point is in the material) |
| `get_assembly_bounding_box` | Tight bounding box of the whole assembly (min/max/size, mm) |
`export` and `screenshot` work on assemblies too.
Faces are selected by direction in the component's **own** frame (`+x`, `-z`, …),
so a selector keeps meaning the same face however the component is turned. Add
`:inner` (e.g. `+y:inner`) for the cavity side of a hollow part — the inside of a
room wall instead of its outer skin.
All linear dimensions are **millimetres**; the server converts to/from the
SolidWorks-internal metre/radian units at the boundary.
## Architecture
```
src/solidworks_mcp/
binding.py early-binding plumbing (wrap raw dispatches in generated classes)
com_worker.py one dedicated STA thread; all COM calls serialised through it
session.py SolidWorks operations (must run on the COM thread)
server.py FastMCP tools that delegate to session via the worker
constants.py enum values read from the installed typelib (verified)
units.py mm<->m, deg<->rad
errors.py SolidWorksError -> agent-facing {ok:false,error}
```
Two non-obvious design decisions, both load-bearing:
1. **Early binding is mandatory.** On this build `GetActiveObject` returns a
dispatch whose `GetTypeInfo()` fails, so `EnsureDispatch`/`CastTo` cannot infer
types and pure late binding breaks (`IModelDoc2.FirstFeature` →
`DISP_E_MEMBERNOTFOUND`). We generate makepy wrappers from the installed
typelib and wrap each raw dispatch in the right interface class; calls then go
by dispid via `InvokeTypes`, bypassing name resolution. See `binding.py`.
2. **A dedicated COM thread.** COM is STA and thread-affine. The MCP server runs
on asyncio, so all COM work is pinned to one worker thread (`com_worker.py`)
that handlers post to and await — actively enforcing the "one COM session,
single-threaded" rule that does not hold automatically in an async server.
## Status and roadmap
Proven end-to-end against **SOLIDWORKS 2026 (3DEXPERIENCE R2026x)**:
| Milestone | What it proves | State |
|---|---|---|
| M0 | COM connection to a running SolidWorks | ✅ |
| M1 | new part → sketch rectangle → extrude → mass properties (volume matches hand calc) | ✅ |
| M2 | change a named dimension → rebuild → volume changes predictably | ✅ |
| M3 | full agent loop via the MCP server: build → measure → correct → export STEP/STL + screenshot | ✅ |
| M4 | revolve, sweep, loft, profiles, holes/pockets/counterbores, slots, fillet/chamfer, shell, patterns, equations, materials, save/open | 🚧 ongoing |
| M5 | end-to-end 3D-print part: build a functional mounting bracket through the full loop → verify every dimension → export a fine STL ([scripts/m5_demo_bracket.py](https://github.com/hjbaard/SolidWorks-MCP/blob/main/scripts/m5_demo_bracket.py)) | ✅ |
| M6 | assemblies: insert and position components, mate them, check interference — every placement and mate measured back ([tests/test_assembly.py](https://github.com/hjbaard/SolidWorks-MCP/blob/main/tests/test_assembly.py)) | ✅ |
See [Docs/PROGRESS.md](https://github.com/hjbaard/SolidWorks-MCP/blob/main/Docs/PROGRESS.md) for the detailed log and roadmap.
Feedback and contributions are welcome.
## Known limitations
- Geometry so far: **boxes**, **cylinders/cones** (revolve), **arbitrary
extruded profiles**, **holes**, **polygon pockets/slots** (`cut_profile`),
**fillets**, **chamfers**, **shells**, **linear + circular patterns** (bolt
circles); plus **equations**, **materials**, geometry **inspection**, and
**save/open** of `.sldprt`, **holes + pockets on any planar face**
(model→sketch transform), **round flanges** (disc + bore + bolt circle), and
**slotted holes** (`cut_slot`, obround at any angle — the first arc-based sketch),
**general revolves** (`add_revolved_profile`: any `(r,z)` profile → shafts,
vases, rings), **swept pipes/tubes** (`add_swept_pipe`: a round profile along
a rounded 2D path), and **lofts** (`add_lofted_solid`: blend stacked polygon
profiles → transitions/adapters), **free-form extrusions**
(`add_extruded_spline`: a smooth closed spline → organic/aesthetic outlines), and
**non-circular sweeps** (`add_swept_profile`: any cross-section along a path →
rails, gaskets, trim), and **mirrors** (`add_mirror`: features or the whole
body about a plane through the part).
- Selection: plane walk, face-by-normal/direction (`_planar_face_by_normal`,
`+z`/…, with `:inner` for the cavity side of a hollow part), and edge selection
by axis **or explicit index** (`_select_edges`). `list_faces`/`list_edges` let
an agent inspect geometry before selecting.
- Assemblies (M6): components, transforms, mates and interference detection.
Component patterns, in-context features, configurations, drawings and
Simulation (FEA) are out of scope.
Connection Info
You Might Also Like
No recommendations available