There are a lot of tools that promise to help you understand existing code. However, it's a really hard problem and to me none of them is production ready. Per

There are a lot of tools that promise to help you understand existing code. However, it's a really hard problem and to me none of them is production ready. Personally, I think the problem is that if the AI got it wrong, it would waste you a lot of time trying to figure out whether it's wrong or not. It's similar to outdated comments.