build123d-mcp lets an AI assistant drive the open-source build123d Python CAD library through MCP to create and edit 3D parts and export them. Agents that output real geometry, not just text, is where AI starts touching design work.
For design and mechanical engineers: who script CAD.
A simulated abrasives plant feeds live OPC UA values to an MCP server that calculates every KPI and traffic light the same way each time, and Claude only picks the tools and writes the answer. It is read only, scopes data by role and logs every tool call.
For plant managers and shift leads: a clean model of how to let AI explain the dashboard without letting it make up the figures.
The authors say real-time AI recommendations that affect the well must work inside a management-of-change framework, with a qualified engineer able to review and override each decision and a full record of actions. Their line: "not autonomous drilling but collaborative intelligence."
Writes stay off unless the server is started with them enabled, and a write is sent once and never retried, so a lost reply comes back as "may have been applied, check first." That is how a tool that can touch a live register should behave.
For controls and instrumentation techs: let an agent pull register values and device IDs for troubleshooting without giving it a way to change anything.