Feb 13, 2026

Last updated on Mar 31, 2026

Claude Code Setup Guide: Install, Permissions, and Your First Workflow

Many developers understand the idea of Claude Code before they understand how to set it up safely in a real repository. The first mistakes are usually not about prompting. They are about installation shortcuts, shell setup, permissions, and starting with a task that is too large to tell whether the setup is actually healthy.

This guide focuses on the shortest practical path: install Claude Code, avoid the common permission mistakes, verify the environment, and start with one bounded workflow you can check afterward.

What Claude Code needs before setup

Anthropic’s official docs list a few practical requirements before installation:

a supported operating system
Node.js 18+ if you are using the npm install path
internet access for authentication and processing

Claude Code works best in a normal shell environment, and Windows users often have a smoother first run in WSL or Git Bash style setups.

How to install Claude Code

Anthropic’s docs show this npm installation command:

npm install -g @anthropic-ai/claude-code

One important warning from the docs is worth following closely: do not use sudo npm install -g for Claude Code. Anthropic specifically warns that this can create permission and security problems.

After installation, verify the CLI:

claude --version

And for a deeper environment check:

claude doctor

That second command is especially useful when something feels slightly off but not completely broken.

How authentication works

Anthropic’s docs say Claude Code requires an eligible account such as Pro, Max, Teams, Enterprise, or Console access. After installation, you log in by running:

claude

Then you follow the browser authentication prompts.

That means the basic setup flow is:

install the CLI
verify the binary
run claude
complete browser login

The permission issue most people hit first

The most common setup problem is not the model. It is local permissions.

In practice, permission issues usually come from:

installing with the wrong npm privileges
unclear shell environment setup
trying to run Claude Code in a directory with restricted access
expecting the agent to edit or run commands without clearly understanding what is allowed

The best pattern is to fix the environment instead of forcing the install with elevated privileges.

What your first workflow should look like

Your first workflow should teach you how Claude Code reads the repo and how it behaves around verification.

If you are still deciding whether Claude Code is the right fit at all, reading the broader Claude Code Review first gives better context before you invest in setup details.

A good first workflow looks like this:

ask Claude Code to explain the repository structure
ask it to locate one important configuration area
make one small safe edit
run one verification command

Example prompt:

Explain where the blog category order is defined, then update one category description and make sure the project still builds.

That gives you repository reading, editing, and verification in one loop without taking on too much risk.

What to define before using it on real work

Claude Code becomes much more reliable when the repo gives it clear operating rules.

This is also where team-specific guidance starts to matter, which is why a follow-up like the Claude Code Skills Guide becomes more useful right after the basic setup is done.

Before larger tasks, define:

build and test commands
file or directory boundaries
naming rules
review expectations
prohibited destructive actions

In real projects, that usually means a useful AGENTS.md, good package scripts, and clear folder conventions.

Common setup mistakes

1. Treating installation success as workflow success

Just because claude opens does not mean the repo workflow is ready.

2. Skipping `claude doctor`

This is one of the easiest ways to catch installation or configuration problems early.

3. Starting with a wide-open feature request

A huge first task usually hides whether the problem is setup, prompt scope, or repository ambiguity.

4. Not telling the tool how to verify changes

If quality matters, give explicit checks like npm run build, tests, or linting.

Once installation is stable, move straight to one small repo task with a verification command instead of jumping into a large feature request.

FAQ

Q. What is the first command I should run after install?

Run claude --version, then claude doctor, then open claude and complete authentication.

Q. Should I use sudo for npm install?

No. Anthropic’s docs explicitly warn against that path because of permission and security issues.

Q. What is the best first workflow?

A repository explanation plus one small edit and one verification command is the safest starting point.

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