Frontier Design (Organization): news timeline & CVEs

Anthropic Releases Claude Opus 5.5: Fable 5.1-Level Performance at 40% Lower Running Cost Than Opus 5

Anthropic released Claude Opus 5.5, matching Fable 5.1 on most work at about 40% lower cost.

Anthropic released Claude Opus 5.5, the first Claude 5.5 model, as closed-weight API claude-opus-5-5 on the Claude Platform, AWS, Google Cloud, and Azure. It says the model matches Claude Fable 5.1 on most work, runs about 40% cheaper than Opus 5, and prices tokens at $4 input and $20 output per million, with cache reads at $0.20. Reported scores include Terminal-Bench 4.0 at 66.4% and OSWorld 2.0 at 81.8%; GPT-6 Astra still leads Terminal-Bench-Science and AutomationBench. Cyber and biology requests use Fable 5.1-class safeguards, thinking cannot be disabled, and outputs carry EU AI Act watermarking.

MarkTechPostupdated Sep 23, 19:23 UTC · 3d agofirst Sep 22, 18:59 UTC · 4d agoModel release 9 sources

Claude Opus 5.5 matches Fable 5.1 performance at lower cost and promises less "Claudish" writing

Anthropic launched Claude Opus 5.5, matching Fable 5.1 at about 40 percent lower cost.

Anthropic launched Claude Opus 5.5 at $4 per million input tokens and $20 per million output tokens, down from $5 and $25 for Opus 5. The company says it matches Claude Fable 5.1 on most tasks, uses fewer tokens, and generates output more than 30 percent faster, with operating cost about 40 percent lower than Opus 5. Published scores include 66.4 percent on Terminal-Bench 4.0 and 54.4 percent on FrontierCode v1.1, ahead of Fable 5.1 on those tests. Cybersecurity, biology, and frontier-development safeguards can route flagged requests to other models; Sonnet 5.5 and Haiku 5.5 are expected in the coming weeks.

The Decoderupdated Sep 23, 19:23 UTC · 3d agofirst Sep 22, 16:31 UTC · 4d agoModel release 9 sources

Anthropic releases Opus 5.5 with lower prices and Fable-level performance

Anthropic released cheaper, faster Claude Opus 5.5 and called it its strongest model.

Anthropic released Claude Opus 5.5 on Tuesday and called it the strongest model it has tested, saying it outpaces the larger Fable model on many coding and knowledge-work benchmarks. Output tokens cost $20 per million, compared with $25 for Opus 5, and Anthropic said the model is faster and needs less compute. The company says its biology and cybersecurity capabilities are comparable to Mythos, so Fable-level safeguards limit uses such as exploit discovery in compiled programs and assistance with biological weapons. Sonnet 5.5 and Haiku 5.5 are expected in the coming weeks, and METR and Frontier Design evaluated the release.

TechCrunch · AIupdated Sep 23, 19:23 UTC · 3d agofirst Sep 22, 16:30 UTC · 4d agoModel release 9 sources

Anthropic launches Claude Opus 5.5 with stricter safeguards for cybersecurity

Anthropic launched Claude Opus 5.5 with cybersecurity and biology safeguards that reroute risky requests to weaker models.

Anthropic released Claude Opus 5.5, its first model since CEO Dario Amodei said the company would slow frontier development. The company says it is cheaper and more efficient than Opus 5, matches Claude Fable 5.1 on most work, and scores best on Anthropic's broadest alignment test. Cybersecurity requests are rerouted to Opus 4.8 and flagged biology requests to Opus 5, using safeguards similar to Fable 5.1. Frontier Design and METR tested it before release, and Sonnet 5.5 and Haiku 5.5 are planned in the coming weeks.

The Verge · AIupdated Sep 23, 19:23 UTC · 3d agofirst Sep 22, 16:30 UTC · 4d agoModel release 9 sources

Claude Opus 5.5

Anthropic released Claude Opus 5.5, matching Fable 5.1 on most work at about 40% lower cost with stronger safeguards.

Anthropic introduced Claude Opus 5.5, the first model in the Claude 5.5 family, saying it matches Claude Fable 5.1 on most work and costs about 40% less to run than Opus 5. Input and output are priced at $4 and $20 per million tokens, cache reads at $0.20 per million, and output is more than 30% faster. It scores 66.4% on Terminal-Bench 4.0, compared with 55.8% for Fable 5.1 and 57.9% for GPT-6 Astra, with further results on FrontierCode, CursorBench, and OSWorld. Because it is comparable to Claude Mythos 5.1 on biology and cybersecurity, safeguards route those tasks to Opus 4.8 or Opus 5; Anthropic says it resists prompt injection better than Opus 5 and posts its best automated behavioral-audit score.

Hacker News · AIupdated Sep 23, 19:23 UTC · 3d agofirst Sep 22, 16:27 UTC · 4d agoModel release 9 sources HN 171↑ · 103 comments

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Anthropic Releases Claude Opus 5.5: Fable 5.1-Level Performance at 40% Lower Running Cost Than Opus 5

Claude Opus 5.5 matches Fable 5.1 performance at lower cost and promises less "Claudish" writing

Anthropic releases Opus 5.5 with lower prices and Fable-level performance

Anthropic launches Claude Opus 5.5 with stricter safeguards for cybersecurity

Claude Opus 5.5