Saeid

Claude Fable 5 will be available again globally tomorrow. After a series of productive conversations with the US government, we're redeploying the model with a new set of classifiers to target and block more cybersecurity tasks. In the near term, some routine tasks like coding and debugging will fall back to Opus 4.8. We’ll continue to refine these classifiers over the coming weeks to reduce false positives and better distinguish genuine misuse from legitimate requests. We’ve also begun drafting a consensus framework—with Amazon, Microsoft, Google, and other Glasswing partners—for assessing the severity of AI jailbreaks and how AI developers should respond to them. We invite other industry partners and model providers to join us in this effort. Finally, we’re scaling up our collaboration with the US government on model testing and safeguards. This will include pre-release access to models and safeguards for evaluation, information sharing on jailbreaks and misuse, and dedicated resources for joint research. Thank you to our users for your patience, and to our partners across the government, industry, and the research community who worked alongside us to make Fable 5 available again. Read our full blog: anthropic.com/news/redeployi…

Claude Sonnet 5 achieves 53 on the Artificial Analysis Intelligence Index, but without promotional pricing will cost more per task than Opus 4.8 We supported @AnthropicAI to evaluate Claude Sonnet 5 ahead of release: with max effort it improves 6 points over Sonnet 4.6 to achieve the same Intelligence Index as GPT-5.5 with high reasoning, but remains behind Opus 4.7 and 4.8 Key takeaways: ➤ Claude Sonnet 5 is the #5 model on the Artificial Analysis Intelligence Index, only 2-3 points behind GPT-5.5 (xhigh) and Opus 4.8 (max) ➤ With max effort, Sonnet 5 works harder than previous Anthropic models: it used ~40% more output tokens per Intelligence Index task than Sonnet 4.6, and ~3x the agentic turns for our knowledge work evaluations AA-Briefcase and GDPval-AA. This behavior scales well with the ‘effort’ setting, with the max effort using around 6x more turns than low effort on GDPval-AA ➤ Claude Sonnet 5 costs more per task than Opus 4.8 before accounting for promotional pricing: Claude Sonnet 5 costs $2.29 per task on the Intelligence Index, a ~2x increase compared to Sonnet 4.6 and ~15% more than Claude Opus 4.8. This is driven entirely by increased token usage. Sonnet 5 retains the same $3/$15 per 1M input/output token pricing as Sonnet 4.6 (compared to $5/$25 for Opus 4.8), however Anthropic is offering a one-third reduction to $2/$10 until September 1. Our results use standard $3/$15 pricing ➤ Sonnet 5 matches or outperforms Opus 4.8 on agentic knowledge work tasks: on both AA-Briefcase and GDPval-AA, Claude Sonnet 5 sits just ahead of Opus 4.8, trailing only Claude Fable 5 (which is not currently generally available). These benchmarks test the ability of models to produce accurate and well-presented professional outputs using our open source reference agent harness, Stirrup ➤ For reasoning and knowledge-heavy tasks, Sonnet still sits behind its larger siblings: despite substantial gains across many evaluations, heavy reasoning and knowledge benchmarks still show Opus 4.8 ahead of Sonnet 5. On CritPt, a frontier physics reasoning benchmark developed by researchers at Argonne and UIUC, Sonnet 5 scores 17% - this is 14 points higher than its predecessor, but behind GLM-5.2, Claude Opus and Fable, and GPT-5.5 (xhigh and Pro) ➤ Sonnet 5 also showed significant improvements over Sonnet 4.6 on Terminal-Bench v2.1 (+9 points), Humanity’s Last Exam (+10 points), and SciCode (+7 points), with relatively flat scores elsewhere Other key model details: ➤ Context window of 1 million tokens (equivalent to Sonnet 4.6) ➤ Pricing of $3/$15 per 1M tokens of input/output (reduced to $2/$10 until September 1); cache pricing remains at a 25% premium for cache writes ($3.75 per million tokens) with 5-minute time to live, and 90% discount for cache hits ($0.3 per million tokens) ➤ Effort remains the recommended way of configuring model performance and latency. Sonnet 5 adds an additional ‘xhigh’ effort setting relative to Sonnet 4.6, matching the 5 effort levels available on Opus 4.8 (max, xhigh, high, medium, low)

Claude Sonnet 5 achieves 53 on the Artificial Analysis Intelligence Index, but without promotional pricing will cost more per task than Opus 4.8 We supported @AnthropicAI to evaluate Claude Sonnet 5 ahead of release: with max effort it improves 6 points over Sonnet 4.6 to achieve the same Intelligence Index as GPT-5.5 with high reasoning, but remains behind Opus 4.7 and 4.8 Key takeaways: ➤ Claude Sonnet 5 is the #5 model on the Artificial Analysis Intelligence Index, only 2-3 points behind GPT-5.5 (xhigh) and Opus 4.8 (max) ➤ With max effort, Sonnet 5 works harder than previous Anthropic models: it used ~40% more output tokens per Intelligence Index task than Sonnet 4.6, and ~3x the agentic turns for our knowledge work evaluations AA-Briefcase and GDPval-AA. This behavior scales well with the ‘effort’ setting, with the max effort using around 6x more turns than low effort on GDPval-AA ➤ Claude Sonnet 5 costs more per task than Opus 4.8 before accounting for promotional pricing: Claude Sonnet 5 costs $2.29 per task on the Intelligence Index, a ~2x increase compared to Sonnet 4.6 and ~15% more than Claude Opus 4.8. This is driven entirely by increased token usage. Sonnet 5 retains the same $3/$15 per 1M input/output token pricing as Sonnet 4.6 (compared to $5/$25 for Opus 4.8), however Anthropic is offering a one-third reduction to $2/$10 until September 1. Our results use standard $3/$15 pricing ➤ Sonnet 5 matches or outperforms Opus 4.8 on agentic knowledge work tasks: on both AA-Briefcase and GDPval-AA, Claude Sonnet 5 sits just ahead of Opus 4.8, trailing only Claude Fable 5 (which is not currently generally available). These benchmarks test the ability of models to produce accurate and well-presented professional outputs using our open source reference agent harness, Stirrup ➤ For reasoning and knowledge-heavy tasks, Sonnet still sits behind its larger siblings: despite substantial gains across many evaluations, heavy reasoning and knowledge benchmarks still show Opus 4.8 ahead of Sonnet 5. On CritPt, a frontier physics reasoning benchmark developed by researchers at Argonne and UIUC, Sonnet 5 scores 17% - this is 14 points higher than its predecessor, but behind GLM-5.2, Claude Opus and Fable, and GPT-5.5 (xhigh and Pro) ➤ Sonnet 5 also showed significant improvements over Sonnet 4.6 on Terminal-Bench v2.1 (+9 points), Humanity’s Last Exam (+10 points), and SciCode (+7 points), with relatively flat scores elsewhere Other key model details: ➤ Context window of 1 million tokens (equivalent to Sonnet 4.6) ➤ Pricing of $3/$15 per 1M tokens of input/output (reduced to $2/$10 until September 1); cache pricing remains at a 25% premium for cache writes ($3.75 per million tokens) with 5-minute time to live, and 90% discount for cache hits ($0.3 per million tokens) ➤ Effort remains the recommended way of configuring model performance and latency. Sonnet 5 adds an additional ‘xhigh’ effort setting relative to Sonnet 4.6, matching the 5 effort levels available on Opus 4.8 (max, xhigh, high, medium, low)