Anthropic has released Claude Opus 4.6, its new flagship model. For the first time, an Opus model features a one million token context window. The company says it can locate relevant information in large documents more reliably than previous models.
Anthropic has released Claude Opus 4.6, an upgrade to the previous flagship Opus 4.5. For the first time, an Opus model can handle a context window of one million tokens, currently available in beta.
However, larger context windows come with a known problem: the more information a model has to process, the worse its performance gets. Researchers call this "context rot." Anthropic says it's addressing this through improvements to the model itself, plus a new "Compaction" feature that automatically summarizes older context before the window fills up.
In MRCR v2, a test that measures how well models can find hidden information in large amounts of text, Opus 4.6 scores 76 percent with one million tokens. The smaller Sonnet 4.5 managed just 18.5 percent under the same conditions.
The model is available on claude.ai, through the API, and on major cloud platforms. Standard pricing is $5 per million input tokens and $25 per million output tokens. For prompts over 200,000 tokens, premium rates apply: $10 for input and $37.50 for output per million tokens.
