The agents tend to produce working code but the larger the scope the bigger the mess they tend to make. They will happily evolve toward a local maxima but leave world-destroying bugs lurking in the implementation.
The other issue is that claude regularly ignores explicit instructions in CLAUDE.md or in prompts. It will "helpfully" decide to just start doing whatever it wants or reinterpret instructions completely differently than it did the last 100 times.
It has nothing to do with losing control or trust. LLMs are not conscious. They have no executive function. They aren't even thinking. They're just models predicting the next word in the script. They are very useful tools but that's all they are: tools.