Fable 5 – Median thinking declined in August
Summary
Lon Lundgren's X thread analyzes a notable drop in Fable 5 performance after Anthropic's subscription change, reporting fewer thinking tokens and inconsistent reasoning. The posts suggest the issue may relate to the inference regime rather than a nerf, and highlight fluctuations tied to product announcements. The piece emphasizes the importance of verifying inference conditions when evaluating frontier models.