Anthropic's first public Mythos-class model is fast, opinionated, and 2× the price of Opus 4.8. After a week of running real marketing jobs through it, here's the actual breakdown — capabilities, costs, the 30-day data retention rule that affects agencies, and the marketer use cases where Fable 5 actually wins.
A reproducible workflow: run a 50K-URL Screaming Frog crawl, dump every relevant tab as CSVs, hand the folder to Claude Code, and get a priority-scored fix list developers can split into Jira tickets by Monday.
