After a few more hours， I think I've figured out Opus 5.
Opus 5 is trained to be more agentic than anything I've used. All Claude 5 models are like that.
So what changes？
The way to interact with Opus 5 or contextualize it won't work the same way as with other models.
It loves exploring， so it doesn't need much guidance for it. Unique preferences， artifacts， and references compliment it well and enable cleaner and more effective exploration and execution.
Now that it can explore more effectively on its own and understand intent better， the best thing to do is to get out of its way （e.g.， it doesn't need examples of your preferences； a clear high-level description of it works best）. It's truly agentic in that sense.
A good first step to provide better context for Opus 5 is to distinguish between what's situational and what needs persistence.
Regardless， persistent system prompts and CLAUDE.MD needs to stay lightweight. Remove memories and tool descriptions from these. CLAUDE.MD is also a great place to tap into progressive disclosure by linking command/skills to it.
On the situational side， agent skills and auto-memory can leverage progressive disclosure and the improved ability of the model to use its external context/knowledge. Conflicting and unnecessary instructions， which are common at this layer （mainly to ensure reliability）， are going to throw off this model easily. That's the biggest change I had to make.
Simple， clean， and clear prompts and skills work best.
I had to clean a lot of my skills and system prompts. The way I prompt remains the same （usually clear and well-scoped）. MCP tool descriptions are also more descriptive and have been deduped from the system prompt.