Claude Code

Overview

Claude Code is an agentic coding tool from Anthropic that lives in your terminal and IDE. It understands your codebase and helps you code faster by executing routine tasks, explaining complex code, and handling git workflows - all through natural language commands. It’s powered by Claude Sonnet 4.5 and can maintain autonomous focus for 30+ hours on complex, multi-step tasks.

Release Timeline

Major Releases

2024-09: First prototype created internally at Anthropic
2024-11: Dogfooding-ready version for internal testing
2025-02-24: Public announcement and limited research preview alongside Claude 3.7 Sonnet
2025-09-29: Claude Code 2.0 released with Claude Sonnet 4.5 - major upgrade with checkpoints, subagents, and hooks
2025-12: Background agents, named sessions, custom rules directory, Claude in Chrome (Beta)

Key Updates (2025)

December: Background agents, named sessions (/rename, /resume), .claude/rules/ directory, prompt suggestions, model switching (alt+p/option+p), /stats command, Chrome integration
July-August: Customizable status line, custom subagents, /export command, drag-and-drop images
April: Tool renaming for consistency, queue messages while working, image file support

Key Features

Autonomous Operation

Active Collaborator: Searches and reads code, edits files, writes and runs tests, commits and pushes to GitHub, uses command line tools
30+ Hour Focus: Maintains focus on complex, multi-step tasks powered by Claude Sonnet 4.5
Feedback Loop: Gather context → take action → verify work → repeat

Checkpoints & Rollback (2.0)

Automatically saves code state before each change
Instant rewind to previous versions (Esc twice or /rewind)
Revert code, conversation, or both

Subagents (2.0)

Spawn specialized AI assistants working in parallel
Independent context windows and tool sets
Delegate subtasks that run concurrently
Example: Backend API development while main agent builds frontend

Hooks (2.0)

User-defined scripts that auto-run at specific workflow points
Enable automated testing, deployment, custom validation

Background Tasks

Long-running processes active without blocking other work

Browser Integration

“Claude in Chrome” (Beta) - control browser directly from Claude Code via Chrome extension

MCP Support

Native MCP integration for hundreds of external tools and data sources
Functions as both MCP server and client
Connect to databases, APIs, services (Slack, GitHub, Asana, etc.)
10,000 token output warning threshold
Configurable limits via MAX_MCP_OUTPUT_TOKENS
Enterprise management with managed-mcp.json

What Makes It Unique

Terminal-Native Approach

Unlike IDE-focused competitors, fundamentally designed for terminal workflows

Superior Context Windows

200,000 token context windows enable awareness of large codebases

Architectural Reasoning

77.2% SWE-bench Verified solve rate (highest among competitors)

Leverages Claude Sonnet 4.5’s advanced reasoning
Plan Mode builds comprehensive understanding of system architecture
Reads documentation and understands patterns
Formulates approaches aligned with existing codebase

Dialogue-Based Debugging

Explains reasoning behind solutions, helping developers understand trade-offs and learn

Multi-Platform Support

Native terminal interface (CLI)
VS Code extension
JetBrains IDE integration
GitHub integration (@claude mentions)
Compatible with Cursor, Windsurf, VSCodium

Technical Architecture

Core Components

Interaction Layer: REPL interface, input processor, output renderer
Core Engine: Coordinates components, manages context and tool execution
MCP Integration Layer: Functions as both MCP server and client

Installation

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

Current Version: 2.0.76 (December 2025)

System Requirements

Minimal requirements - standard Unix-like environments
Supported: macOS, Linux, WSL on Windows
Requires: Terminal access and internet connectivity
Lightweight - runs on workstations to modest laptops
Performance determined by network latency vs local computation

VS Code Extension

Native graphical interface integrated into VS Code
Review and edit plans before accepting
Auto-accept edits as they’re made
@-mention files with specific line ranges
Real-time diffs with accept/reject buttons
Multiple conversations in separate tabs
Install: Cmd+Shift+X (Mac) or Ctrl+Shift+X (Windows/Linux), search “Claude Code”

Pricing (2025)

Free Tier

No Claude Code access
Basic Claude.ai chat only (~10 messages daily to Claude Sonnet)

Pro Plan - $20/month

Entry-level Claude Code access
40-80 hours weekly Sonnet 4 usage
~10-40 prompts every five hours
Suitable for individual developers on small-medium projects

Max Plan

$100/month: 5x Pro usage
$200/month: 20x Pro usage

Team Plan - $150/user/month

Premium seats with enhanced coding capabilities
Enterprise-grade features

Alternative: GitHub Copilot includes Claude 3.7 Sonnet (February 2025 public preview) with unlimited usage for flat monthly fee

Comparison to Other Tools

vs Cursor

Cursor Strengths: AI-powered code editor (VS Code fork), project-aware, multi-file refactoring, 39% increase in merged PRs in studies
Claude Code Strengths: Terminal-native, 77.2% SWE-bench score, 200K context windows, 30+ hour autonomous operation

vs GitHub Copilot

Copilot Strengths: Most widely used, affordable ($10/month), excellent autocomplete and snippet completion
Claude Code Strengths: Architectural reasoning, dialogue-based debugging, autonomous long-running tasks

Recommendation: Use different tools for different purposes - Copilot for affordable MVP development, Cursor for advanced multi-file work, Claude Code for complex architectural reasoning and autonomous tasks

Claude Agent SDK

The Claude Agent SDK exposes the same tools, context-management systems, and permissions framework that power Claude Code. Available in Python and TypeScript for building custom AI agents for any domain.

Key SDK Features

Autonomous workflow loop (same as Claude Code)
Built-in tools for bash, file operations, web search
Automatic compaction and context management
Rich tool ecosystem with MCP extensibility
Released September 2025 (v0.1.x)
TypeScript V2 interface preview (late 2025) with simplified session-based API

Explorer