Anthropic shipped Claude Sonnet 5 as "our most agentic Sonnet yet," but the reaction was unusually sour: multiple analysts pointed out it scores below Opus 4.8 on nearly every benchmark and even trades blows with open-weight GLM-5.2, fueling a narrative that Anthropic is degrading tiers on purpose. The concrete details still landed — a $2/$10 promo price, a 1M-context variant, a January 2026 cutoff, and instant availability in Claude Code, Cursor, and Raycast.
The sharpest critique compared it point-by-point to Opus 4.8, the specs leaked a day early, and the counter-take was that it matches Opus on agentic and computer-use tasks for far less — with its real competitor arguably being GLM-5.2, and it showing up in Claude Code on day one.