SolidWorks MCP Server

A Node.js MCP server for automating SolidWorks via COM interop. Connects AI assistants (Claude Desktop, etc.) to SolidWorks for CAD automation tasks.

Project Status: Alpha / Experimental

This project is under active development. While the architecture is in place and basic operations (sketch planes, simple extrusions) have been demonstrated, most tools have not been validated against a live SolidWorks instance. Expect rough edges, COM quirks, and incomplete functionality. Contributions and testing reports are very welcome.

How It Works

The server exposes SolidWorks operations as MCP tools over stdio. An intelligent routing layer handles a key limitation of Node.js COM bridges: methods with 13+ parameters often fail via direct COM calls.

• Simple operations (12 params or fewer) - Direct COM call via winax
• Complex operations (13+ params) - Auto-generated VBA macro executed by SolidWorks
• Failed operations - Automatic fallback with error context

Prerequisites

• Windows 10/11 (required - COM interop is Windows-only)
• SolidWorks 2021-2025 (licensed, installed)
• Node.js 20+
• An MCP-compatible client (Claude Desktop, etc.)

Installation

git clone https://github.com/vespo92/SolidworksMCP-TS.git
cd SolidworksMCP-TS

# Install dependencies (compiles winax native module for your system)
npm install

# Build TypeScript
npm run build

Note: The winax native module must be compiled locally on each Windows machine. Global npm installation does not work.

Configure Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "solidworks": {
      "command": "node",
      "args": ["C:/path/to/SolidworksMCP-TS/dist/index.js"],
      "env": {
        "SOLIDWORKS_PATH": "C:\\Program Files\\SOLIDWORKS Corp\\SOLIDWORKS",
        "ADAPTER_TYPE": "winax-enhanced"
      }
    }
  }
}

Available Tools

The server registers tools across these categories:

"Partially tested" means the tool has been run against SolidWorks at least once but not comprehensively. "Untested" means only mock/unit tests exist (if any).

Architecture

MCP Protocol (stdio)
    |
Tool Registry (index.ts)
    |
Feature Complexity Analyzer --- routes by param count
    |                    |
Direct COM (winax)    VBA Macro Generator
    |                    |
    +--------------------+
    |
SolidWorks COM API

Key Design Decisions

• COM parameter limit workaround: SolidWorks API methods like FeatureExtrusion3 take 20+ parameters. Node.js COM bridges choke on these. The complexity analyzer detects this and generates a VBA macro instead.
• Never pass null to COM: Use undefined for optional parameters. COM interprets null as VT_NULL, causing type mismatch errors (this was the root cause of SelectByID2 failures).
• Feature tree traversal over SelectByID2: FeatureByPositionReverse() + GetTypeName2() is more reliable for finding sketches than SelectByID2.
• Winston logger only: Never use console.* - it corrupts the JSON-RPC stdio transport.

Development

npm run build        # TypeScript compile
npm run dev          # Hot-reload dev server (tsx watch)
npm run check        # TypeScript + Biome lint in one command
npm run lint         # Biome lint check
npm run lint:fix     # Biome auto-fix
npm run format       # Biome format
npm run typecheck    # Type check without emit

Testing

See TESTING.md for the full testing guide.

# Unit tests (mock adapter, no SolidWorks needed)
USE_MOCK_SOLIDWORKS=true npm test

# Watch mode
npm run test:watch

Current test status: Unit tests exist for config and environment utilities. Most tool modules lack test coverage. Integration tests require a Windows machine with SolidWorks and have not been run in CI.

Known Issues & Limitations

• No CI integration testing - Tests only run against mocks. Real SolidWorks integration tests require a self-hosted Windows runner that doesn't exist yet.
• winax compilation - Must be compiled locally on each machine. No pre-built binaries.
• Edge.js adapter - Defined in architecture but not implemented.
• PowerShell bridge - Defined in architecture but not implemented.
• Connection pooling / circuit breaker - Referenced in code but not battle-tested.
• Performance metrics are unverified - No real benchmarking has been done.

What Has Worked

Based on development testing:

• Connecting to a running SolidWorks instance via COM
• Creating sketch planes and basic sketch geometry
• Simple extrusions with limited parameters
• Feature tree traversal for sketch selection
• VBA macro code generation (execution path needs more testing)

Roadmap

• Comprehensive integration test suite on real SolidWorks
• CI with self-hosted Windows runner
• Validate all modeling tools end-to-end
• Validate drawing and export tools
• Edge.js adapter for .NET runtime path
• PowerShell bridge as alternative COM path
• Performance benchmarking with real metrics

Contributing

See CONTRIBUTING.md for guidelines.

Key areas where help is needed:

• Testing against real SolidWorks - The biggest gap. If you have SolidWorks, running tools and reporting results is extremely valuable.
• COM interop edge cases - Different SolidWorks versions behave differently.
• Additional tool implementations - Many SolidWorks API methods aren't exposed yet.

Troubleshooting

For winax native build failures on Windows 11 Build 26200+ / VS 2022 BuildTools 17.14+ (issue #23) and other install-time problems, see TROUBLESHOOTING.md.

COM Registration Issues

regsvr32 "C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\sldworks.tlb"

Build Issues

rm -rf node_modules dist
npm install
npm run build

Debug Logging

ENABLE_LOGGING=true LOG_LEVEL=debug node dist/index.js

License

MIT - See LICENSE

Acknowledgments

• winax - COM bridge for Node.js
• Anthropic MCP - Model Context Protocol
• SolidWorks API documentation