Claude Code - Anthropic's AI Coding Assistant CLI

What is Claude Code?

Claude Code is a terminal-based AI coding assistant developed by Anthropic. It allows you to leverage Claude’s powerful coding capabilities directly from the command line, without depending on editors like VS Code.

Reference: Claude Code - Anthropic

Key Features

1. Agentic Coding

Claude Code isn’t just a code generation tool—it’s an agent that understands your entire project and executes tasks autonomously.

# Installation (via npm)
npm install -g @anthropic-ai/claude-code

# Launch
claude

# Or specify a task directly
claude "Run the tests in this project and fix any failures"

Note: Installation methods may change. Check the official documentation for the latest information.

2. Context Awareness

Automatically analyzes project structure and understands related files before responding.

Project Analysis:
├── package.json (dependencies)
├── tsconfig.json (TypeScript config)
├── src/ (source code)
└── tests/ (test files)

3. Multi-File Editing

Execute changes across multiple files at once.

# Example: Adding authentication
claude "Add JWT-based authentication to the API.
Create middleware, routes, and tests."

# Claude Code automatically:
# - Creates src/middleware/auth.ts
# - Creates src/routes/auth.ts
# - Creates tests/auth.test.ts
# - Adds dependencies to package.json

Useful Features

Slash Commands

Tool Calls

Claude Code uses these tools to execute tasks:

Available Tools:
- Bash: Execute shell commands
- Read: Read files
- Write: Create/overwrite files
- Edit: Partial file editing
- Glob: File pattern search
- Grep: Text search
- WebFetch: Fetch web information

Usage Examples

Bug Fixing

claude "I'm getting TypeError: Cannot read property 'map' of undefined
in src/components/List.tsx. Fix it."

# Claude Code will:
# 1. Identify the cause
# 2. Propose a fix
# 3. Apply after user approval

Refactoring

claude "Split src/utils/helpers.ts into smaller modules.
Move each function to appropriate files and update imports."

Test Creation

claude "Create unit tests for src/services/userService.ts.
Use Vitest and set up mocks appropriately."

Git Operations

claude "Review the changes and commit with an appropriate
commit message."

# Or
claude "/commit"  # Dedicated commit command

MCP Server Integration

Connect with external tools using Model Context Protocol (MCP).

// ~/.claude/settings.json
{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_TOKEN": "your-token"
      }
    },
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres"],
      "env": {
        "DATABASE_URL": "postgresql://..."
      }
    }
  }
}

Security

Sandboxed Execution

Dangerous operations run in a sandbox and require user approval.

# Example of dangerous operation
claude "rm -rf node_modules && npm install"

# Claude Code: Execute this operation?
# [y] Yes  [n] No  [e] Edit

Permission Management

# Allow access to specific directories only
claude --allowed-paths ./src,./tests

# Read-only mode
claude --read-only

Pricing

Claude Code uses pay-as-you-go pricing based on Claude API rates.

Reference: Anthropic Pricing

Comparison

Installation

# Install via npm
npm install -g @anthropic-ai/claude-code

# Set API key
export ANTHROPIC_API_KEY=your-api-key

# Launch
claude

Summary

Claude Code is a powerful AI coding assistant for terminal users.

• Agentic: Understands entire projects and works autonomously
• Multi-File: Batch editing across multiple files
• Secure Design: Sandbox and approval workflow
• Extensible: External tool integration via MCP

A tool that significantly improves development efficiency on the command line.