Fable 5 is the biggest step up I've felt in our models since Opus 4.5 back in November. After 4.5 came out I uninstalled my IDE when I realized that I'd been doing 100% of my coding in a terminal for a few weeks. With Fable， it's felt like Claude has stepped up from being a coding agent to a thought and design partner in building the product. Fable has judgement， taste， and dimensionality in a way that previous models didn't， leading me to trust it more with the most complex work.

I think the first time I had this realization was when I asked Fable to debug something. It is the first model I have used that was so methodical and precise， taking measurements and adding logs then verifying that it truly fixed the issue before declaring victory.

There's nothing in claude code's prompting telling the model to do that， it's just part of its personality. It really has this "big model smell" that I haven't felt before.