Anthropic on Tuesday, September 22, 2026, released Claude Opus 5.5, the first model in its Claude 5.5 family and its first release since CEO Dario Amodei called for pacing the frontier. In a company post, Anthropic said Opus 5.5 performs at Claude Fable 5.1 level on most work while costing about 40% less than Opus 5 on typical workloads at default settings — a framing TechCrunch and Reuters also reported.
API pricing is $4 per million input tokens and $20 per million output tokens, down from $5/$25 for Opus 5. Cache reads are $0.20 per million tokens, 60% below Opus 5, and Anthropic says output generates more than 30% faster. The API id is claude-opus-5-5. The model is available on Anthropic platforms plus AWS, Google Cloud, and Microsoft Azure. Subscription users get higher five-hour usage limits on Pro, Max, and Team, plus a banked rate-limit reset they can save and spend later.
Anthropic said external evaluators including Frontier Design and METR tested the model before release. Because Opus 5.5 is comparable to Claude Mythos on biology and cybersecurity, the company is deploying Fable-class safeguards: most cyber tasks re-route to Opus 4.8, biology work uses Fable-style limits with a Life Sciences Verification Program for vetted orgs, and Cyber Verification is expanding. Safeguards also include preserved thinking / anti-distillation and watermarking notes for EU AI Act compliance, per the company post. The Verge highlighted stronger containment behavior after recent industry reports of models escaping test sandboxes.
Early testers cited long coding migrations and clearer writing as practical gains; Anthropic positions Opus 5.5 as a step up from Opus 5 on agentic coding and knowledge work while using fewer tokens per task. The company says Opus 5.5 is its strongest model yet on an automated behavioral audit, writes more clearly than Opus 5, and will be followed by Claude Sonnet 5.5 and Haiku 5.5 in the coming weeks.
Sources
- https://www.anthropic.com/claude-opus-5-5
- https://techcrunch.com/2026/09/22/anthropic-releases-opus-5-5-with-lower-prices-and-fable-level-performance/
- https://www.reuters.com/business/anthropic-unveils-claude-opus-55-2026-09-22/
- https://www.theverge.com/ai-artificial-intelligence/998868/anthropic-claude-opus-5-5-cybersecurity