Custom Instructions & Styles
Tired of repeating "be concise" or "I'm a nurse, explain accordingly" every chat? Custom instructions and styles let you set your defaults once and have them apply everywhere.
Custom instructions = your personal system prompt
Set standing facts and preferences — who you are, what you do, how you like answers — and Claude applies them across conversations. It's the consumer-app version of a system prompt (and the cousin of CLAUDE.md for developers).
Good things to include:
- Context about you ("I run a small bakery"; "I code in Python").
- Output preferences ("default to short bullet answers"; "always show your reasoning").
- Hard rules ("never use emoji"; "metric units").
Styles = presentation presets
Styles change tone/format (concise, formal, explanatory, etc.) and can be switched per conversation. Use a style when you want a different voice for this chat without rewriting your standing instructions.
How they stack
More specific/later context tends to win when there's a conflict — so a Project's instructions or an explicit ask in your message can override your global defaults. Keep them consistent to avoid surprises.
Tips
- Keep instructions short and true — like CLAUDE.md, bloat and stale rules hurt.
- Don't put secrets in custom instructions.
- Revisit them occasionally as your needs change.