Claude Fable is kinda bad.
Explored it for 2 days now for variety of tasks and generally it's not much smarter but burns a shit ton of tokens over longer period of time.
So basically they just made the prompts run longer but it's not a linear gain. This kinda makes sense for putting a dumb agent to scan for 0-days with a 1m $ tokens so you can hack a web browser and this explains why they changed the sales angle from productivity to security recently.