No
I haven't been able to use it for anything even with being in the CVP. It downgrades to Opus every time
prettyblocks on Hacker News
In the thread “Claude Fable 5.1 and Claude Mythos 5.1”, replying to this comment
Got in the way: Model downgrades to Opus every time in their environment.
It's probably a good model for folks doing basic software stuff, or humanities related tasks, but I work in cybersecurity on the defense/detections side and I haven't been able to use it for anything even with being in the CVP. It downgrades to Opus every time.