Slash commands are the hidden superpower of Claude Code.

Most people use /init, then forget the system exists. That is leaving 80% of the productivity on the table.

Used right, slash commands turn Claude Code into an opinionated CLI: one keystroke = one repeatable workflow. Let's walk through the built-ins, then build a project from empty folder to running app using nothing but slash commands.

The four built-ins worth knowing

/init

Run this once per project. It creates .claude/ with settings.json, CLAUDE.md, and agents/. Without it, every session starts cold.

/agents

Opens the sub-agent picker. Sub-agents are specialized Claude personas (we cover the full set in Article 5). Use /agents to invoke code-reviewer, test-writer, migration-runner etc. without retyping their system prompts.

/compact

The most underrated. As a session grows, the context window bloats with old tool calls and discarded files. /compact re-summarises the conversation while keeping decisions intact.

/clear

Nuclear option. Drops the entire history. Useful when you switch from "implementing feature X" to "debugging unrelated CI failure" — fresh context, fresh attention.

Custom commands — the real game

Custom commands live in .claude/commands/<name>.md. They are just markdown files that get pasted into the conversation when you type /<name>.

Example: /feature

.claude/commands/feature.md:

You are about to implement a new feature.

Use this template:

# Goal
{{describe the outcome with a number where possible}}

# Constraints
- Do not break existing tests.
- Do not add a new dependency without asking.
- Keep changes scoped to the listed files.

# Definition of Done
- pnpm test passes.
- pnpm lint clean.
- Add a PR description (1 paragraph).

# Files
{{list the relevant files}}

Wait for the user to fill the blanks before starting.

In your terminal:

> /feature

Claude Code expands it. You fill the blanks. Now your prompt structure is enforced — every feature gets the same shape.

Example: /test-and-fix

.claude/commands/test-and-fix.md:

1. Run `pnpm test`.
2. If failures: read each failing test, infer the bug, fix the code (not the test), rerun.
3. Stop only when `pnpm test` exits 0.
4. Report a 3-line summary of what was changed.

Now /test-and-fix is a one-keystroke "go fix the build" command. Beautiful for triaging a flaky CI.

Example: /release-notes

.claude/commands/release-notes.md:

1. `git log --oneline ${LAST_TAG}..HEAD`
2. Group commits into: features / fixes / chores.
3. Write a changelog entry in markdown, no fluff, max 25 lines.
4. Save to CHANGELOG.md and stage it.

A to Z — building a project with only slash commands

Let's prove the point. We are going to scaffold a small Next.js + tRPC service from an empty folder, with one rule: no manual code edits, only slash commands and prompts.

mkdir todo-service && cd todo-service
claude

Inside Claude:

> /init

→ Creates .claude/ and asks for a CLAUDE.md. Fill it:

# Project context
- Small Next.js 14 + tRPC + drizzle service for todos.
- TS strict, pnpm, vitest.

# Conventions
- Test: pnpm test
- Lint: pnpm lint
- Format: pnpm fmt

# Definition of done
- Tests pass, lint clean, no console.log in src/.

Then:

> /feature
> Goal: Bootstrap Next.js 14 app with tRPC + drizzle (sqlite) and a todos table.
> Constraints:
>   - pnpm only.
>   - Use the official create-next-app + tRPC starter, not a fork.
>   - Strict TS.
> Definition of Done:
>   - pnpm dev runs.
>   - GET /api/trpc/todos.list returns [].
> Files: (empty repo)

Claude scaffolds, installs, runs the dev server, hits the endpoint to verify, returns a diff.

> /feature
> Goal: Add POST todos.create with zod validation, persist to drizzle.
> Constraints:
>   - Reuse drizzle client in lib/db.ts.
>   - 1 vitest covering create + list.
> Definition of Done:
>   - vitest green.
>   - typecheck clean.
> Files: src/server/api/routers/todos.ts, lib/db.ts

Claude writes the procedure, the schema, the test, runs it, returns a diff.

> /test-and-fix

If anything broke, it fixes it.

> /release-notes

Changelog written.

> git checkout -b feat/todos && git add . && git commit -m "feat: todos.create + list"

You did not open a single file. The diff is reviewable; the work is done.

Anti-patterns

• /feature without filling the blanks. Defeats the purpose; the agent guesses.
• Custom commands that just echo a paragraph. A custom command should encode a workflow (steps, checks), not just a tone.
• Storing slash commands outside the repo. Commit .claude/commands/ so the team gets the same vocabulary.

The team angle

When .claude/commands/ is in git, you are essentially shipping shared muscle memory. New hires inherit your /feature, /review, /release-notes for free. After 3-4 weeks every team I've worked with has 8-12 custom commands and onboarding time on Claude Code drops from "a week" to "a morning."

---

Next article: Sub-Agents — The 11 Specialized Experts Inside Claude Code. Slash commands let you reuse prompts. Sub-agents let you reuse whole personas. That is the unlock.