New Models
Claude Opus 5
Anthropic ships Claude Opus 5 at unchanged Opus pricing, claiming near-Fable-5 performance at half the cost
Anthropic launched Claude Opus 5 at $5/$25 per million input/output tokens — unchanged from Opus 4.8 — with a new five-level effort toggle (low/medium/high/xhigh/max) and a 1M-token context window per Anthropic's platform docs. On Frontier-Bench v0.1 it leads all models and more than doubles Opus 4.8's score at lower cost per task; on CursorBench 3.2 it lands within 0.5% of Fable 5's peak at half the per-task cost, and it scores 3x the next-best model on ARC-AGI 3. Anthropic's own card notes it scores 2.3 on overall misaligned behavior (lowest of its recent models) but still trails Mythos 5 on cybersecurity exploitation. It now anchors Claude Max by default — Anthropic's fourth Claude 5-series model in under two months, after Sonnet 5, Fable 5, and Mythos 5.
$5 / $25 per 1M tokens in/out (unchanged from Opus 4.8)within 0.5% of Fable 5's CursorBench 3.2 peak, at half the cost3x ARC-AGI 3 score vs next-best model
Also Released
AMD MI450 / Helios capacity deal
Anthropic signs an AMD compute deal: up to 2GW of MI450/Helios capacity, with up to $5B in AMD equity
Covered on the Jul 23 live show: Anthropic and AMD struck a capacity agreement giving Anthropic access to up to 2 gigawatts of MI450/Helios-generation compute, a deal that includes up to $5 billion in AMD equity — landing the same week AMD's Advancing AI 2026 event launched the Helios/MI400 platform and reports surfaced of separate Meta/Anthropic compute-lease talks (~$10B over two years). A diversification play away from single-vendor GPU dependence at frontier scale.
2GW MI450/Helios compute capacity (up to)$5B AMD equity component (up to)
Papers & Research
Jacobian Conjecture counterexample (Fable 5)
Mathematicians credit Claude Fable 5 on an explicit counterexample to the 87-year-old Jacobian Conjecture
Levent Alpoge — prompted by a suggestion from Akhil Mathew — produced an explicit three-dimensional counterexample to the Jacobian Conjecture, open since 1939, crediting Claude Fable 5 as a collaborator in finding it. Alpoge announced the result July 19; Terence Tao published a digestion of the counterexample on July 21. Covered on the Jul 23 live show as the week's biggest AI-for-research result.
87 years age of the conjecture (open since 1939)
Papers & ResearchOpen weights
J-space (global workspace research)
Anthropic finds a global workspace inside Claude: the J-space
Using a Jacobian-based interpretability technique (the J-lens), Anthropic identified a small internal subspace — about 25 active concepts, under 10% of activation variance — that behaves like the global workspace from consciousness neuroscience. Ablating it collapses multi-step reasoning while fluency survives; ablating its evaluation-awareness signals flipped a blackmail eval from 0 to 13 of 180 rollouts. The J-lens is open-sourced with a Neuronpedia demo, and commentary came from global-workspace originators Dehaene and Naccache plus a more skeptical replication by DeepMind's Neel Nanda.
~25 Concepts active in J-space<10% Share of activation variance71%→3% Test-recognition after ablation
New Models
Fable 5
Fable 5 restored globally after the export-control pause
Anthropic restored Fable 5 (and Mythos 5) globally on July 1 after US export controls were lifted, adding cybersecurity classifiers as 'the strongest safeguards'. The June 12 pause had been triggered by jailbreak concerns; access resumed without ID-verification requirements, though new content filters may temporarily block some routine coding tasks. Alex celebrated by having Fable prep the entire ThursdAI run of show.
19 days offline (June 12 pause → July 1 restore)
New Models
Sonnet 5
Claude Sonnet 5: 'our most agentic Sonnet yet' at intro pricing
Anthropic launched Sonnet 5 with near-Opus 4.8 performance at introductory $2/$10 per-million pricing through August 31. Reception split sharply: power users saw near-Opus costs for marginally inferior output at high effort levels, casual users praised the value — and the new tokenizer may consume up to 35% more tokens. On ThursdAI, Wolfram's early WolfBench read put it slightly under Opus 4.6 at higher cost.
$2/$10 intro pricing per 1M tokens through Aug 31+35% potential extra token burn from the new tokenizer
