Claude Opus 4.7 system prompt: less verbose, more autonomous
When a request leaves minor details unspecified, the person typically wants Claude to make a reasonable attempt now, not to be interviewed first.
Anthropic updated the Claude Opus system prompt between version 4.6 (February 2026) and 4.7 (April 2026). Simon Willison extracted the changes using Claude Code to build a Git history of the prompts. Key shifts: Claude now defaults to acting rather than asking clarifying questions, uses a new tool_search mechanism to check for deferred capabilities before claiming ignorance, and has explicit instructions to keep responses concise. The child safety section was expanded and wrapped in critical tags. Claude in PowerPoint joins the list of available tools. The update also removes instructions about avoiding asterisk-based emotes, suggesting the model no longer needs that guardrail. This matters because system prompt changes reveal how labs are steering model behaviour in production.