[acpdev]

25 years experience, work at an AI startup building AI dev tools (tooling harness, review bots, etc), I use lots of different techniques all the time to test our products and competitors products out.

Fable is at once amazing and awful. I can see how having it build websites would be awesome.. building anything I’ve needed some precision in functionality it has been a constant battle of it plausibly building something then on substantial manual digging (like the review bots always miss it) I will find that one of the fundamental features is all smoke and mirrors.

To be fair all models can and will do this (especially anthropic) but Fable takes the cake because it builds such impressive UX and you can manually test the feature out and it « works » then you will find days later one of the features violated one of your constraints in a devilishly fiendish way.. that is not at all what you want or can accept. Fable generated work already holds my record for the most reverted commits.

To be clear it’s also solved several features I thought I was going to have to give up on and hand code as GPT-5.5 and Opus-4.x we’re failing miserably.

I would only reach for it for nasty corner cases that everything else sucks at.

Final point, it is the king of UX work so far, not even close.