Opus 4.6: Anthropic's Most Capable Model Shows Why We Need Independent Verification

Opus 4.6 performs better on long-context retrieval and long-context reasoning, helping avoid “context rot,” and also features a 1M token context window — a first for Opus-class models. Anthropic has upgraded Claude’s integration in applications like Powerpoint and Excel and stresses the new model’s applications in everyday tasks like financial analyses and presentations.

Anthropic has also bulked up its safety protections. In the model release announcement, the company writes that “these intelligence gains do not come at the cost of safety.” Its system card states that Opus 4.6 is as well-aligned as its predecessor, Opus 4.5, with the lowest rate of excessive refusals of any recent Claude model. Anthropic presents results from a range of new and upgraded safety tests covering user well-being, refusals, interpretability, and misaligned behaviors such as deception, sycophancy, encouragement of user delusions, and cooperation with misuse. The company has also published new safeguards in areas with dual-use concerns, like cyber and bio-risks, and argues that Claude should be used to “level the playing field” against bad actors by accelerating cyber-defensive applications like finding and patching vulnerabilities in open-source software.