Create .claude/commands/ when you have well defined repeatable, multi-step actions you want to take. I have a command `/triage` where I provide it a bug report and it asks me questions to start scaffolding a work area, lookup related issues, create patches, etc.

Create .claude/agents/ when you have a narrow scoped thing that you want to happen, but not pollute the main context and have a well formed output. Also handy for reducing costs by using a different model for a class of actions you repeat often. For example, the "lookup related issues" from `/triage` is a Sonnet agent that finds Trac issues for a bug reports. Main context only needs the small list of matches and not the dozens of not relevant ones.

Create .claude/skills/ for job description like behaviors you want. For example, code reviewer or security researcher.

For any of these, install the `/plugin` skill-creator. Run `/init` if you don't have a claude.md and then ask the skill creator to help you improve the claude.md and create useful commands and skills.