Claude Fable 5.1 and Mythos 5.1: The System Card
Zvi (Don't Worry About the Vase) TheZvi ● Covered by 4 sources
Claude Fable 5.1 and Mythos 5.1 system cards describe how Anthropic’s updated models change safety, cyber, alignment, and welfare results compared with prior releases. The bio benchmark LatchBio Bioinformatics improved from 72.5% to 77.6%, while alignment risk is reported as “low” rather than “very low” in the accompanying risk update. Overall, the update is presented as incremental with stronger cyber/classifier defenses and some modest capability gains, while retaining similar conclusions about CB-2 and autonomy risk.
Why it matters
At the time of its release Claude Fable 5.1 was, by a healthy margin, the most capable publicly available AI model in the world. As per usual, we have a 200+ page model card, and the assessments start there. We … Continue reading →
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