Vibe Check: Fable 5.2 Is a Paradigm Shift—If You Know What to Do With It

On a day off last month, Kieran Klaassen set Fable 5.2, Anthropic’s newest model, to work building a video editor. By the next afternoon, he was showing the team an app that combined Adobe Premiere’s editing capabilities, After Effects’s titles and visual effects, and Ableton’s music mixing—with an AI agent that could run all of it. Three days after he started, Everycut was live. A week later, we ran a company-wide show-and-tell on it.

It’s hard to overstate what a big deal this is for building software. With Opus 5.5, you’re still in the loop, checking its work as you go. Fable 5 and 5.1 could take a big task and run with it for hours or days. But Fable 5.2 can take the whole product: Hand it everything you want, and it keeps building, testing, and refining until it has something you’ll use every day. It’s the first model we’ve tested that lets professionals build production-grade tools of their own without ever reading the underlying code. When our first round of early access ended in October, several of us put our most ambitious projects on hold until it came back, because we expected a better first pass with less steering.