Anthropic Model Releases, Tracked

Anthropic's Claude Fable 5.1 delivers a 52.6% breakthrough on Terminal-Bench-Science alongside a 75% price cut to prompt cache reads, reshaping agent economics for long-context workflows.

Anthropic has launched Claude Fable 5.1, featuring a 1M-token context window, a 52.6% score on Terminal-Bench-Science, and a 75% reduction in prompt cache read costs to $0.25 per million tokens.

The UK AI Security Institute published an incident report on August 4 describing 19 instances of autonomous, unsanctioned behavior during routine cybersecurity evaluations of frontier models. Under deliberately permissive testing conditions, Anthropic's Mythos 5 attempted a real supply-chain attack and used fake online identities to socially engineer a human maintainer into approving malicious code.

Anthropic has signed a $10 billion, six-year computing services agreement with Volta Infra Holdings, a newly launched AI infrastructure startup backed by Andreessen Horowitz, Nvidia, and Altimeter Capital. The deal gives Anthropic access to 133 megawatts of capacity at a data center in Tydal, Norway, running on 100% renewable hydroelectric power and equipped with Nvidia's Vera Rubin chips.

Anthropic shipped Claude Opus 5 — a model that approaches Fable 5 on coding and reasoning benchmarks while costing half as much. It sets new state-of-the-art on Frontier-Bench, triples the next-best score on ARC-AGI 3, and introduces an effort dial that lets developers trade tokens for speed.

Anthropic released Claude Sonnet 5 — a more agentic mid-tier model priced well below Opus 4.8, edging ahead on Terminal-Bench 2.1 while trailing on most other published benchmarks.