Sure they’re fine at that sort of rote find/replace job as long as it’s relatively straightforward. But it only really works if you do the hard parts yourself then tell the agent to go and do the rote part. Even then I’ve had it turn to slop more often than not as the agent has to start contorting the code into weird shapes to try and finish the job. It’ll never stop and be like “hey maybe this was a bad idea, let’s try something else”. And by the time you get to review it, you’ve spent 20 bucks on something that needs to be thrown away.