Can ChatGPT write AutoLISP?

Yes, and so can Claude and Gemini. The routine usually loads, but layer names, units and edge cases (an ssget that returns nil) are guesses until you run it. An assistant that runs it in the drawing closes that loop.

Does cadssistant show me the LISP it runs?

Yes. Every expression it runs appears in the chat with the value AutoCAD returned, and you can ask for any routine as a .lsp file.

Does it use Visual LISP (vla-, vlax-) functions?

Where they're the right tool: curve lengths and areas, block effective names, properties entmod can't reach. They run in full AutoCAD, which is where cadssistant runs.

Is it safe to let an AI run AutoLISP in my drawing?

The chat's Revert takes the drawing back to where the turn started. Read-only questions run no editing command. Work on a copy for anything you can't afford to redo.

Guides

Is there an AI that writes and runs AutoLISP inside AutoCAD?

Yes. Any chatbot can write AutoLISP; the difference is who runs it and whether the result is checked. ChatGPT or Claude in a browser give you a routine to paste and debug yourself. An MCP connector such as autocad-mcp lets Claude Desktop send AutoLISP into AutoCAD, including AutoCAD LT 2024 and newer. cadssistant runs inside AutoCAD 2024+ as a palette: it writes an AutoLISP expression, evaluates it directly in your session, reads the value back, and corrects it when it fails, with every expression visible in the chat. No API key or Claude subscription is needed. Examples: count blocks by name, renumber tags, centre marks on every circle, fix a failing routine.

Checked 2026-10-24

Three ways to get AutoLISP from an AI

A browser chatbot (ChatGPT, Claude, Gemini) writes a routine from your description. You save it as a .lsp, load it with APPLOAD and run it. It never sees the drawing, so layer names, units and the empty-selection case are guesses until you try it. Good for a first draft; the debugging is yours.
An MCP connector gives a desktop AI app tools that reach into AutoCAD. The open-source autocad-mcp drives AutoCAD through AutoLISP and works in AutoCAD LT 2024+; HuskyBIM and AEC Pilot's bridge do similar for full AutoCAD. You bring the Claude plan and do the setup; the chat is in a separate window.
An assistant inside AutoCAD. cadssistant evaluates AutoLISP in the session it runs in, reads the result back and retries on error, with the models included. It also runs plain commands and asks for points and selections through AutoCAD's own prompts, so a routine rarely needs getpoint at all.

How cadssistant runs AutoLISP

It runs AutoLISP in your open drawing and reads back what AutoCAD returned, which is how it knows a count, a list of objects or an error message. Every expression it runs is shown in the chat with its result.

It prefers plain AutoLISP (ssget, entget, entmake, entmod and commands) over the Visual LISP ActiveX functions. When it needs a point, a distance or a selection it uses AutoCAD's own prompt rather than a getpoint in the routine, so you pick in the drawing and Esc cancels.

Revert in the chat takes the drawing back to where the turn started. Read-only questions change nothing in the drawing.

Keeping what it wrote

Ask for the routine as a defun and save it as a .lsp to load anywhere, AutoCAD LT included if it uses nothing from Visual LISP.
Save the prompt as a command: type CADWALLS at the command line and the saved sentence runs in the chat, with {parameters} asked for like a built-in command.

What it won't do

It doesn't run in AutoCAD LT. AutoCAD LT is not supported yet: it doesn't run the JavaScript the palette is built on. A chatbot's AutoLISP, or autocad-mcp, is the LT route; see AI for AutoCAD LT.
It won't guess silently. A missing radius or spacing gets a stated default; a missing target gets a prompt in the drawing.

AutoLISP from an AI, three ways

	Sees the drawing	Runs the code	Reads the result	Fixes its own errors	AutoCAD LT
Browser chatbot	No	No, you load it	No	No, you paste the error back	You load it in LT 2024+
MCP connector (autocad-mcp, HuskyBIM)	Through its tools	Yes	Yes	Yes, in the desktop app	autocad-mcp: yes
cadssistant	Yes	Yes, in the session	Yes, in the chat	Yes	No

Questions

Can ChatGPT write AutoLISP?: Yes, and so can Claude and Gemini. The routine usually loads, but layer names, units and edge cases (an ssget that returns nil) are guesses until you run it. An assistant that runs it in the drawing closes that loop.
Does cadssistant show me the LISP it runs?: Yes. Every expression it runs appears in the chat with the value AutoCAD returned, and you can ask for any routine as a .lsp file.
Does it use Visual LISP (vla-, vlax-) functions?: Where they're the right tool: curve lengths and areas, block effective names, properties entmod can't reach. They run in full AutoCAD, which is where cadssistant runs.
Is it safe to let an AI run AutoLISP in my drawing?: The chat's Revert takes the drawing back to where the turn started. Read-only questions run no editing command. Work on a copy for anything you can't afford to redo.

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