[Claude Code Primer] Core Features and Getting Started with a Terminal-Based AI Coding Agent

AI-powered coding tools are multiplying, but Claude Code has carved out a unique position as a CLI (terminal)-first agentic tool. Its defining feature is the ability to handle code generation, editing, debugging, and Git operations end-to-end based on natural language instructions. This article provides a clear explanation of Claude Code's core concepts, features, use cases, and setup steps.

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What Is Claude Code?

Claude Code is an agentic AI coding tool from Anthropic that you control through a terminal, IDE, or web browser using natural language — while it understands and works across your entire project. Unlike traditional completion-based tools, its key differentiator is the ability to make project-wide changes and execute end-to-end workflows using natural language.

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Claude Code Features and Capabilities

Understanding the Full Project Context

Claude Code reads not just individual files but the entire repository's structure and dependencies, then applies changes based on your natural language instructions. It can handle large-scale tasks like refactoring and spec changes that span multiple files.

Code Generation and Editing via Natural Language

Simply instruct it in natural language and it will handle new code generation, feature additions, bug fixes, and improvement suggestions. Unlike traditional comment-based completion, it generates high-quality change proposals by referencing project context.

Git Workflow Automation

Claude Code supports Git operations as well — you can create branches, commit, and generate pull requests (PRs) in natural language. This streamlines the AI-assisted workflow from code changes through review.

Claude Code's Key Extensions

Claude Code goes beyond code generation; it includes a set of capabilities that enhance extensibility for each project. This section explains the roles and distinctions of three key mechanisms: Skills, Custom Commands (Slash Commands), and Subagents.

Skills

Skills are reusable specialist knowledge packages that extend Claude Code's capabilities. Skills are placed in directories such as .claude/skills/ and add modular, task-specific rules and knowledge to Claude. Claude autonomously decides when to invoke the appropriate skill based on the prompt and context.

Characteristics

• Specialized knowledge: Define team-specific coding conventions, output formats, and more
• Reusability: Define once, share across multiple projects
• Auto-application: Claude automatically invokes skills when the situation calls for them

Examples

• Rule definitions for automated API test generation
• Documentation generation templates
• Coding conventions and auto-formatting

Skills fundamentally extend Claude's internal knowledge level, making domain expertise available more efficiently than standard prompts or CLAUDE.md.

Custom Commands (Slash Commands)

Custom Commands are a way to define frequently used tasks or complex procedures as shortcuts that can be called directly from the CLI. Custom commands are primarily defined in .claude/commands/.

Characteristics

• User-initiated: Execute defined commands on demand
• Simplifying repetitive work: Run repeated prompts or combinations of multiple commands as a single command

Examples

• "/generate-tests": Auto-generate tests command
• "/clean-logs": Log file cleanup command

Custom commands are best suited for situations where you want to trigger an action explicitly.

Subagents

Subagents are independent AI agents specialized for specific tasks, each with their own context window and settings. When a specific task is detected within a Claude Code workflow, processing is delegated to the appropriate subagent.

Characteristics

• Independent context: Can process separately from the main conversation history
• Role specialization: Handles specialized processing such as test generation, code review, and API design
• Parallelism: Multiple subagents can be launched in parallel

Subagents are autonomous execution agents suited for specialist and complex workflows.

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When to Use Custom Commands, Skills, and Subagents

By choosing the right tool for the job, you can get the most out of Claude Code's extensions:

1. When you want to speed up everyday routine tasks

→ Custom Commands

Turn frequently occurring tasks into shortcuts to eliminate the overhead of issuing the same prompt every time.

2. When you want to share knowledge and rules across the entire project

→ Skills

Define team-specific best practices and rules, and have them applied automatically whenever needed.

3. When you want to autonomously handle specialist or multi-step tasks

→ Subagents

Run agents with clearly defined roles (e.g., code review, test design) independently, then return results to the main flow.

Example combination

A practical pattern is having a subagent handle a complex workflow while skills supply the domain expertise.

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Where Claude Code Shines

Claude Code is effective in the following use cases:

• Large-scale refactoring: Automate changes spanning multiple files
• Spec-to-implementation automation: Natural language spec → code generation → Git operations
• Specialist processing workflows: Delegate test generation and quality checks to dedicated subagents
• Auto-applying team rules: Use skills to enforce coding conventions and templates consistently

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Getting Started with Claude Code (Setup)

1. Account and Plan

First, you'll need to sign up for an Anthropic Claude plan (Pro/Max, etc.) to use Claude Code.

2. Installation

Install the official CLI in your terminal and navigate to your project root.

Typically:

npm install -g claude-code

Install the CLI like this (follow the official documentation for actual steps).

3. Running Your First Project

Just type a natural language command in your project root, and Claude Code will read the context and begin processing.

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Common Pitfalls for Beginners

• Confirm safe operations: Always review the Preview → Approve flow for large-scale changes and Git operations
• Organize your project context: Keep your CLAUDE.md, skill files, and subagent definitions in order
• Understand the pricing model: Know your token consumption and plan limits to avoid overspending

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Summary

Claude Code is a development platform that goes beyond simple completion tools, enabling you to drive your entire project in collaboration with AI. It handles code generation, editing, Git operations, and workflow automation via natural language — and the extensibility of Custom Commands, Skills, and Subagents takes the developer experience even further. Understand these features and their distinctions, and leverage Claude Code in the way that best fits your project.

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Related: when the terminal and Git are what trip you up

For beginners, the sticking point with Claude Code is usually terminal and Git operations rather than the tool itself. Once you can read a change with git diff and undo it with git reflog, the Preview → Approve flow starts functioning as real review. Free ways to start are compared in "CLI and programming study in the age of AI coding agents".