Reverse Engineered Onshape for MCP Server

An MCP server for AI-assisted CAD in Onshape. It exposes Onshape's native editor commands and browser-authenticated REST calls through a local API, using a small extension connected to your signed-in browser. No Onshape API keys required.

Use it with Codex, Claude Code, or another client supporting local stdio MCP servers. Give your agent an Onshape URL or ask it to use the current Onshape tab.

Install uv and your AI client first. Then run this command in Terminal or PowerShell:

uv run --python 3.12 https://raw.githubusercontent.com/godbrigero/onshape-native/main/install.py --client codex

Replace codex with claude, both, or generic. Add --directory "PATH" to choose where the source and extension live. For a local checkout, run uv run --python 3.12 install.py --client codex instead.

The installer downloads the server, creates its Python environment, generates private pairing data on your device, and registers the selected client. generic generates a .mcp.json entry to import into your client's MCP settings.

Finish in your browser: open its extensions page, enable Developer mode, choose Load unpacked, and select the extension folder printed by the installer. Sign in to Onshape, then restart your AI client. Browser approval cannot be automated by this installer.

The AI client, server and Chromium browser must run on the same computer. The installer handles macOS, Linux and Windows paths; full browser setup has been tested on macOS only. See installation and updates.

Discover commands, inspect geometry, and edit sketches, features and assemblies.

Traverse and edit tabs, folders and feature trees; inspect mass and materials.

Control visibility, camera views and mate motion; capture the viewport.

Return compact summaries, with complete saved details available through one tool: artifact_page.

It prefers backend commands and provides UI fallbacks where needed. This is an unofficial, reverse-engineered integration: complete Onshape API/UI parity is not guaranteed, and native commands can change with Onshape releases.

uv sync --frozen uv run pytest uv run python scripts/package.py

Generated launchers, pairing tokens, caches and environments stay local and are excluded from source control and release ZIPs. Response formats · Measured token savings · Modeling skill