swagent

An MCP server that lets an AI agent drive a local SOLIDWORKS installation over COM: sketch, extrude, revolve, drill, pattern, mirror, shell, chamfer, build drawings, save, export and screenshot — with a measured number returned for every modelling call.

Built because the existing SolidWorks MCP servers assume SOLIDWORKS is already running, target versions newer than 2022, and give you no way to tell a silent no-op from a successful feature.

MCP client  ──stdio JSON-RPC──▶  swagent  ──comtypes/COM──▶  SLDWORKS.exe 2022
                                    │
                                    └─ every call: measure volume, abort if unchanged

• Protocol: MCP over stdio, JSON-RPC 2.0, newline delimited

• Tools: 39 (see docs/TOOLS.md for the per-tool verification status)

• Engine: comtypes bound directly to sldworks.tlb

• No other third-party dependencies. Pure-Python BMP→PNG so screenshots need no Pillow.

Both parts are modelled entirely through this server: one tooth plus a circular pattern for the gear, extrude-drill-revolve for the shaft. Their volumes are checked against the closed-form value in the examples, to three decimals.

Status (honest)

Tested on one machine: Windows 11, SOLIDWORKS 2022 SP05, Chinese UI, network (SolidNetWork) licence. That is where the numbers below come from. Everything else is untested — treat it as "works in principle, verify on yours".

Related MCP server: SolidworksMCP-python

Requirements

• Windows, SOLIDWORKS 2022 or later installed (the type library is found through the registry, so no path configuration is needed)

• Python 3.10+ and pip install comtypes

• SolidWorks must be licensed and launchable by the same user account that runs the server

Two environment quirks we hit, which you may or may not have:

• on that machine the VBA 7.1 engine only initialises for an elevated process, and an unelevated SolidWorks then reports success while writing 0 bytes. If saves behave strangely, run the host and SOLIDWORKS both as administrator.

• the licence was a campus network licence, unreachable without VPN. sw_status probes the licence before launching and fails with a readable error instead of hanging on a dialog.

Install

git clone https://github.com/<your-account>/swagent.git
cd swagent
python -m venv .venv
.venv\Scripts\pip install -e .

Check it without touching SOLIDWORKS:

.venv\Scripts\python -m swagent --version
.venv\Scripts\python -m swagent --list-tools
.venv\Scripts\python tests\test_offline.py       :: 15 checks, no SolidWorks needed
.venv\Scripts\python tests\probe_protocol.py     :: real stdio handshake

Wire it into an MCP client

- id: mcp-solidworks
  name: '@deepseek-ai/dsh-mcp-client'        # or any MCP stdio client
  config:
    serverName: solidworks
    transport: stdio
    command: 'D:\path\to\swagent\.venv\Scripts\python.exe'
    args: ['-m', 'swagent']
    toolCallTimeoutMs: 600000

For Claude Desktop the same thing in claude_desktop_config.json:

{
  "mcpServers": {
    "solidworks": {
      "command": "D:\\path\\to\\swagent\\.venv\\Scripts\\python.exe",
      "args": ["-m", "swagent"]
    }
  }
}

Tools in one screen

sw_status · sw_new_part · sw_open_part · sw_close_part · sw_list_features · sw_mass_properties · sw_rebuild · sw_view · sw_screenshot · sw_save · sw_export · sw_set_dimension · sw_add_box · sw_add_cylinder · sw_add_profile · sw_cut_hole · sw_cut_pocket · sw_counterbore · sw_gear · sw_fillet · sw_chamfer · sw_shell · sw_revolve · sw_circular_pattern · sw_linear_pattern · sw_mirror · sw_offset_plane · sw_delete_feature · sw_new_assembly · sw_add_component · sw_list_components · sw_add_mate · sw_new_drawing · sw_add_drawing_view · sw_standard_views · sw_drawing_annotations · sw_add_configuration · sw_activate_configuration · sw_family_table

Full schemas: python -m swagent --list-tools, or read swagent/tools.py.

Design notes

1. Measure, don't trust. Every modelling call takes the volume before and after and raises cut_failed / extrude_failed if it did not move. This is how a silently ignored FeatureExtrusion2 was caught; the API had returned an object and built nothing.

2. Write whitelist. resolve_output() only allows the package directory and its parent; extend it with SWAGENT_OUTPUT_ROOTS. Requests outside it fail with path_not_allowed.

3. Errors are objects, not tracebacks: {"code": "not_connected", "message": …, "hint": "Connect to the VPN that serves the licence server, then call sw_status again."}

Configuration

Known limits

• Argument counts were measured against the 2022 typelib. Another SolidWorks year may add or drop a parameter and produce TypeError: call takes exactly N arguments; see docs/PITFALLS.md for how to re-measure in ten minutes.

• sw_add_mate, sw_linear_pattern, sw_drawing_annotations are wired but not verified.

• Single-view drawing API (CreateDrawViewFromModelView3) returns nothing on 2022 SP05; only the four-view Create3rdAngleViews2 route is used.

• Holes must be positioned on extruded faces. On a revolved body the face sketch frame is not the part origin, so model "extrude the flange → drill → revolve the body" instead.

• No surface modelling, sheet metal, weldments, simulation or CAM.

Examples

examples/gear.py and examples/shaft.py rebuild the two parts in this repo's screenshots, both checked against an analytic volume. Run them with an elevated interpreter:

.venv\Scripts\python examples\shaft.py

License

MIT. SolidWorks is a trademark of Dassault Systèmes; this project is unaffiliated and only talks to a licensed installation you already own.

中文说明见 docs/中文说明.md。