Anthropic says outdated prompting habits are slowing down Claude Opus 5.5

Anthropic says users of Claude Opus 5.5, now the default on Pro, Max, Ultra, and Team plans, should drop phrases like "think hard" because the model always reasons on its own and scales depth to the task and effort level. The company recommends starting at the default "Medium" effort, which it says matched Opus 5 on "High" in internal tests, and describing the desired end result in a single message rather than giving instructions one at a time. Anthropic also advises attaching diagrams and tables as files, naming unwanted design styles specifically, and connecting files and systems via connectors.