I feel this mostly is a side effect from lack of domain knowledge. Most of the time this has happened to me, it's because I myself did not cleanly know how a problem should be solved to begin with. If you have a clear picture of what you want, approximately what syntax goes where and why, thats really when LLMs shine in my experience.

Yeah but on the other hand, if you asked an LLM to implement a spec and it was like “I skipped this part because I didn’t like the complexity tradeoff” most people would be like “wtf why doesn’t Claude just listen to me”

I found it follows conventions and documentation well. So if you have a well designed core, it can easily add independent features without increasing overall complexity. Maybe it doesn't work in some very tangled domains like games, but some basic crud and saas stuff is pretty much a solved problem now with agents. They will trivially add features that humans would have pushed to a backlog forever as not worth the effort.

If you tell it to implement something it will go ahead and implement it, without considering how much complexity it adds to the system or weighing alternatives.

Recently I asked Claude (Fable) to use multiple threads to speed up a computation that could take several seconds to run while the user was waiting. Instead, it found a way to start the computation earlier in the background while the user was doing other things, so that it would be finished by the time the user was ready.

Have you found any solutions to this? It would be a big unlock to give it this kind of judgement