HN Explorer

Ask HN: How to rewrite `Claude.md` and install the skill for Opus5 and Fable5

5 points by hyhmrright ↗ HN
Anthropic has released the new Opus 5 and Fable 5 models. Many existing resources—such as `claude.md` files and custom skills—are no longer compatible with these new models. How should one rewrite or adjust `claude.md`, or develop skills better suited to these models?

7 comments

[ 0.63 ms ] story [ 34.7 ms ] thread
gojkoa
where did you get the "are no longer compatible" part? we moved from opus 4 to opus 5 without changing anything and no specific conflicts. used fable for a while, also did not have to change anything. I read some advice on the anthropic website that opus 5 doesn't require as many examples as before, but this was a recommendation how to make things shorter, not a backwards compatibility issue.
hyhmrright
Thanks; the issue likely stemmed from the translation software used previously. I’ve seen many people online mention that removing skills like "superpowers" reduces token consumption and shortens completion times. I also read that Anthropic removed over 80% of the system prompts for Claude Code. I’m interested in finding out how to adjust `claude.md` and the installed skills to better optimize performance for the Opus 5 and Fable 5 models.
alvis
These models don't take claude.md, Claude Code does, and claude.md still get fed to these models if you're using Claude Code.

That said, prompting on opus 5 needs new technique: https://platform.claude.com/docs/en/build-with-claude/prompt...

hyhmrright
Thanks; the issue likely stemmed from the translation software used previously. I’ve seen many people online mention that removing skills like "superpowers" reduces token consumption and shortens completion times. I also read that Anthropic removed over 80% of the system prompts for Claude Code. I’m interested in finding out how to adjust `claude.md` and the installed skills to better optimize performance for the Opus 5 and Fable 5 models.
BearBest
You need to distinguish between the model and the agent. claude.md skills rules are handled by the agent.

The model is similar to the brain, and the agent is similar to the hands. The brain directs the hands to take claude.md skills rules and other resources to feed the brain.