What Claude Code is and why it is different
Claude Code is a coding agent that lives in your terminal. Instead of copying snippets out of a chat window, you point it at a real repository and it reads files, writes edits, runs your tests, and loops until the task is done. That single difference — direct access to your filesystem and shell — is what makes it an agent rather than an assistant. It can reproduce a bug, write a failing test, fix the code, and confirm the test passes, all without you shuttling text back and forth. The cost of that power is responsibility: it can also delete files or run destructive commands, which is why the permissions model and version control matter from the first session.
Core concepts: context, CLAUDE.md, and slash commands
The agent only knows what is in its context window, so managing context is the core skill. CLAUDE.md is the foundation — a file at your repo root that loads automatically every session and carries your architecture, coding standards, test commands, and hard rules. Encode anything you would otherwise repeat. Keep it tight; a bloated CLAUDE.md wastes the budget the agent needs for actual work.
Slash commands are reusable prompts. Built-in ones like /clear reset context between unrelated tasks, and you can define your own for repeated workflows such as code review or releasing. Use /clear aggressively: a fresh context for each distinct task keeps the agent focused and cheaper than dragging a long, irrelevant history through every turn.
The permissions model
Every action that touches your system — running a command, editing a file — passes through permissions. By default the agent asks first. You can approve once, allow a tool for the rest of the session, or pre-approve safe patterns in your settings so routine reads and edits do not interrupt you. The rule that prevents disasters is simple: never blanket-approve destructive shell commands like rm -rf, git reset --hard, or git clean. Keep those gated behind an explicit prompt every time, even when everything else flows freely.
Best practices for safe, fast use
Work on a branch and commit before any large change, so a bad edit is one git checkout away from undone. Review diffs before accepting them — treat the agent as a fast junior developer whose output you always read. Give it strong, verifiable success criteria (“make this test pass”) rather than vague goals (“fix it”), because clear targets let it loop to completion without interrupting you. For independent work, run parallel sub-agents but isolate their file scopes to avoid collisions, and use git worktrees when you need genuine concurrency. Finally, prefer many small, well-scoped tasks over one giant prompt: smaller tasks fit in context, verify cleanly, and are easy to review.