Claude Code: The Complete Guide to AI-Assisted Development

What is Claude Code?

Claude Code is Anthropic's command-line interface (CLI) tool that brings Claude's intelligence directly into your terminal. Unlike browser-based AI assistants, Claude Code works where you work - in your development environment.

Think of it as having a senior developer pair programming with you, but one who can:

• Read and understand your entire codebase
• Edit multiple files simultaneously
• Run terminal commands and tests
• Manage git operations
• Debug complex issues across your project

It's particularly powerful for complex tasks that require understanding context across many files - something that chat-based AI tools struggle with.

Installation & Setup

Getting started with Claude Code takes just a few minutes.

Prerequisites

• Node.js 18 or higher
• npm or yarn
• An Anthropic API key (get one at console.anthropic.com)

Install via npm

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

Set your API key

# Add to your shell profile (.bashrc, .zshrc, etc.)
export ANTHROPIC_API_KEY="your-api-key-here"

# Or set it inline when running
ANTHROPIC_API_KEY="your-key" claude

Verify installation

claude --version

Basic Usage

Once installed, using Claude Code is straightforward. Navigate to your project directory and start a session.

Start a session

# Navigate to your project
cd /path/to/your/project

# Start Claude Code
claude

Common commands

# Start with a specific task
claude "Add user authentication to this Express app"

# Resume a previous session
claude --resume

# Start in a different directory
claude --cwd /path/to/project

Interactive mode

Once inside a Claude Code session, you can:

• Type natural language requests
• Ask follow-up questions
• Review proposed changes before accepting
• Run commands directly

Best Prompts for Claude Code

The quality of your prompts directly affects the quality of Claude Code's output. Here are tested prompts that work well.

For starting new features

Add a user dashboard page that shows:
- Total orders in the last 30 days
- A chart of revenue over time
- List of recent notifications
Use the existing design system and database models.

For refactoring

Refactor the authentication module to:
1. Use async/await instead of callbacks
2. Add proper error handling with custom error classes
3. Implement rate limiting
Keep all existing tests passing.

For debugging

The checkout flow is failing intermittently with a
"payment_intent_unexpected_state" error.

Debug this by:
1. Finding where the error originates
2. Adding logging to track the payment state
3. Identifying the race condition
4. Implementing a fix

For code review

Review the recent changes in the /src/api folder for:
- Security vulnerabilities
- Performance issues
- Code style inconsistencies
- Missing error handling
Provide specific recommendations with code examples.

For documentation

Generate comprehensive JSDoc comments for all
exported functions in /src/utils. Include:
- Parameter descriptions
- Return value documentation
- Usage examples
- Edge cases

When to Use Claude Code

Claude Code shines in specific scenarios. Understanding when to use it helps you maximize productivity.

Perfect for:

• Building new features end-to-end: Claude Code can create routes, components, database models, and tests in one session
• Large-scale refactoring: Rename patterns, update APIs, or restructure code across hundreds of files
• Complex debugging: When bugs span multiple files or involve race conditions
• Adding tests: Generate comprehensive test suites that actually understand your code
• Code migrations: Upgrade dependencies, change frameworks, or update to new patterns
• Project scaffolding: Set up new projects with proper structure, configs, and tooling

When NOT to Use Claude Code

Claude Code isn't always the right tool. Sometimes simpler options work better.

Use Cursor instead for:

• Quick single-file edits: Cursor's Cmd+K is faster for small changes
• Real-time autocomplete: Cursor provides instant inline suggestions
• Visual diffs: When you want to see changes side-by-side in an IDE

Use GitHub Copilot instead for:

• Line-by-line coding: Copilot's autocomplete is smoother for writing new code
• Boilerplate generation: Quick function signatures, loops, etc.

Use v0.dev instead for:

• UI component generation: v0 is purpose-built for React/Next.js UI
• Design exploration: When you need to see multiple visual options

Tips & Tricks

Power user techniques to get the most out of Claude Code.

1. Provide context upfront

Start sessions by explaining your project structure:

This is a Next.js 14 app with:
- App router in /app
- Server actions in /actions
- Drizzle ORM with PostgreSQL
- Tailwind + shadcn/ui for styling

Now, add a user settings page...

2. Use CLAUDE.md files

Create a CLAUDE.md file in your project root with persistent context:

# CLAUDE.md

## Project Overview
E-commerce platform built with Next.js 14

## Tech Stack
- Frontend: Next.js 14, React 18, Tailwind CSS
- Backend: Next.js API routes, Drizzle ORM
- Database: PostgreSQL on Supabase
- Auth: NextAuth.js with Google/GitHub providers

## Conventions
- Use server components by default
- All database queries go through /lib/db
- Use Zod for validation
- Error handling: throw AppError classes

3. Review before accepting

Always review proposed changes. Type diff to see what will change before confirming.

4. Use specific file references

# Instead of:
"Update the user model"

# Be specific:
"In /src/models/user.ts, add an 'avatar' field
and update the schema validation in /src/schemas/user.ts"

5. Break complex tasks into steps

For large features, work incrementally:

# Step 1: Database
"Add the subscription tables and relations"

# Step 2: Backend
"Create the subscription API endpoints"

# Step 3: Frontend
"Build the subscription management UI"

# Step 4: Integration
"Connect everything and add Stripe webhooks"

6. Let it run tests

Claude Code can run your test suite. Use this to verify changes:

"After making changes, run the test suite and
fix any failures before finishing."

Claude Code vs Alternatives

How does Claude Code compare to other AI coding tools?

The winning combo

Many developers use multiple tools together:

• Claude Code for complex features, refactoring, and debugging
• Cursor for day-to-day coding and quick edits
• v0.dev for generating UI components

Pricing & Cost Management

Claude Code uses Anthropic's API, which means you pay per token used.

Current pricing (as of 2025)

What does this mean in practice?

• Light session (quick edits): ~$0.10 - $0.50
• Medium session (new feature): ~$1 - $5
• Heavy session (large refactor): ~$5 - $20

Cost-saving tips

• Be specific in your prompts to reduce back-and-forth
• Use CLAUDE.md files to avoid repeating context
• Break large tasks into focused sessions
• Use Claude 3.5 Sonnet for most tasks (Opus only when needed)
• Set spending limits in your Anthropic console