Cheatsheets

Prompt modes

Mode	How to activate	What Claude can do	When to use
Default	Launch Claude Code (always on by default)	Read files, edit files, run commands	Most everyday work
Plan	Shift+Tab twice, or /plan	Read and reason only — no edits, no commands	Before large or risky changes
Accept edits	Shift+Tab once	Auto-apply file edits without per-change confirmation	Trusted batch edits after reviewing a plan

Input prefixes

Prefix	Name	Purpose	Example
@	File reference	Include a specific file or directory in context	@src/model.py
!	Shell command	Run a command inline and pass its output to Claude	! pytest tests/ -v
&	Background task	Run a command in the background; Claude keeps responding	& python src/train.py

Term definitions

Term	Definition
Token	The basic unit of text processed by the model. Roughly 3–4 characters or ¾ of an English word.
Context window	The total space available for the current session: CLAUDE.md + conversation + files + tool outputs.
Input tokens	All tokens sent to the model in a request. Includes everything in the context window at that moment.
Output tokens	Tokens in Claude’s response. Billed at a higher rate than input tokens.
/cost	Claude Code command that reports token usage and estimated cost for the current session.

Model cost tiers (relative)

Model	Speed	Cost	Best for
Haiku	Fastest	Cheapest	Quick lookups, simple edits, high-volume tasks
Sonnet	Balanced	Mid-range	Default for most Claude Code work
Opus	Slowest	Most expensive	Complex reasoning, architecture decisions

Exact per-token pricing changes. Check anthropic.com/pricing for current rates.

Techniques at a glance

Technique	When to use	Token impact
@file	Target a specific file	High — avoids broad exploration
cd into subdirectory	Working on one component	Medium — narrows file discovery scope
/clear	Starting a new, unrelated task	High — resets full history
/compact	Mid-task, context growing large	Medium — compresses history to summary
Trim CLAUDE.md	Always — keep under 500 words	Medium — saves tokens on every session
Move instructions to skills	When instructions are task-specific	Medium — loads only when invoked
MCP retrieval tool	Large codebase, semantic search needed	High — loads relevant chunks, not whole files

All commands

Command	Purpose	Example
claude	Open interactive session	$ claude
claude "..."	Session with initial prompt	$ claude "explain src/pipeline.py"
claude --model <id>	Open session with specific model	$ claude --model opus
claude --help	Show CLI flags	$ claude --help
/help	List all slash commands	/help
/clear	Wipe conversation history	/clear
/compact	Compress history, keep recent context	/compact
/cost	Show token usage and cost	/cost
/model	Switch model mid-session	/model
/plan	Toggle Plan mode (no file edits)	/plan
/init	Generate CLAUDE.md for current project	/init
! <cmd>	Run shell command inline	! git status
& <cmd>	Run command in background	& python src/train.py
@<file>	Add file to context (input prefix, not a command)	@src/train.py

Where commands live

.claude/
└── skills/
    ├── review-notebook/
    │   └── SKILL.md          # → /review-notebook
    ├── summarize-pr/
    │   └── SKILL.md          # → /summarize-pr
    └── check-leakage/
        └── SKILL.md          # → /check-leakage

Naming convention

• Directory name becomes the command name
• Use kebab-case: review-pr, not reviewPR or review_pr
• Keep names short and action-oriented: /doc, /review, /test

SKILL.md structure

---
name: review-notebook
description: Review a Jupyter notebook for reproducibility and data leakage
---
Review the notebook at $ARGUMENTS for...

$ARGUMENTS syntax

You type	$ARGUMENTS value
/review src/model.py	src/model.py
/compare models/v1.pkl models/v2.pkl	models/v1.pkl models/v2.pkl
/review (no argument)	(empty string)

How to invoke

Skills in .claude/skills/ are loaded automatically — no activation step needed.

$ claude
> /review-notebook notebooks/churn_model.ipynb
> /summarize-pr #87
> /check-leakage src/features/