Anthropic warns outdated prompts slow Claude Opus 5.5

anthropic advises users of claude opus 5.5 to update their prompting habits, as outdated methods can slow the model. specifically, phrases like 'think hard' or 'think carefully' are no longer needed and can delay responses without improving quality. the company recommends starting at the medium effort level, which matches the performance of opus 5 on high effort. describing desired results directly, attaching files and diagrams, and naming specific design styles also improve performance. teams are advised to reconsider using cheaper sonnet for complex projects, as opus 5.5 can complete tasks in fewer steps, offsetting its higher cost.