Mythos 5.1, Fable 5.1 and Opus 5.5: Model Welfare
If you are familiar with my previous posts on model welfare for new Claude models, you can skip the Introduction and The Story So Far.
Proof1 independent outlet
Key points
- This post goes over model welfare and related concerns, the same way I previously did for Fable and Mythos 5, Opus 5, Opus 4.8 and Opus 4.7.
- Events overtook me before I could post this for Mythos and Fable 5.1, so I am combining the reports there with the one for Opus 5.5, along with selected other related observations.
- Introduction (As Per Prior Model Welfare Posts).
- Model Welfare: The Story So Far (As Per Fable Model Welfare Post).
Sources (1)
- [1]Mythos 5.1, Fable 5.1 and Opus 5.5: Model WelfareDon't Worry About the Vase (Zvi) · Oct 5, 02:12 PM
If you are familiar with my previous posts on model welfare for new Claude models, you can skip the Introduction and The Story So Far.
This post goes over model welfare and related concerns, the same way I previously did for Fable and Mythos 5, Opus 5, Opus 4.8 and Opus 4.7.
Extractive summary: sentences quoted from the sources.
Before this
- Oct 5, 2026Sharing AI progress in mathematics
- Oct 3, 2026[AINews] not much happened today
- Sep 30, 2026Gemini 4 Argon: our next era of frontier intelligence
- Sep 30, 2026Last Week in AI #345 - 5 new models, 9 misalignment incidents, some Dots
- Sep 29, 2026Astra 6.1 Pulled As Insufficiently Aligned
- Sep 29, 2026Claude Code’s Next Era — Thariq Shihipar, Anthropic
