How do I add my own /command to Claude Code?

A slash command is a markdown file. That’s the whole feature.

1. Pick a scope

• Project: .claude/commands/<name>.md — committed with the repo, shared with the team.
• User: ~/.claude/commands/<name>.md — only on your machine, available everywhere.

If a command exists in both, the project version wins.

2. Write the file

.claude/commands/review-pr.md:

---
description: Review the current branch's diff for SQL safety and missing tests
---

You are reviewing the diff against `main`. Focus on:

1. SQL queries — are parameters bound? Any string concatenation into SQL?
2. New code paths without tests.
3. Side effects inside conditionals (logging, mutation, network).

Report findings as a numbered list. Do not modify any files.

The diff:

!`git diff main...HEAD`

Two things to notice:

• The description shows up in the command palette.
• The backtick-bang syntax !`...` runs a shell command and inlines its output. That’s how you give commands access to live state.

3. Use it

In a session, type /review-pr. The full markdown body becomes the prompt, with the git diff substituted in.

4. Add arguments

If you want /review-pr api to scope the review, use $ARGUMENTS:

Review only the files under `$ARGUMENTS` for SQL safety...

When to write one

The bar is low: any prompt you’ve typed twice is worth a slash command. Three times and you’re being silly not to.