Claude Code is Anthropicās terminal-first agentic coding assistant. Unlike IDE-based tools that offer autocomplete, Claude Code operates as an autonomous agent: reading your entire codebase, executing shell commands, running tests, and self-correcting based on errors without constant human oversight.
Core Philosophy
Terminal-native autonomy over IDE integration. You describe what you want, Claude Code figures out how to build it across multiple files, runs tests to verify, and commits when done. Delegation over collaboration.
Key Capabilities
- Codebase understanding: Maps and explains entire codebases in seconds using agentic search
- Multi-file editing: Coordinates changes across files based on architectural understanding
- Git workflow automation: Reads issues, writes code, runs tests, submits PRs from terminal
- Self-correction: Iterates on compiler errors and test failures without human intervention
- Extended autonomy: Sonnet 4.5 sustains ~30 hours of continuous agentic operation
Architecture
Claude Codeās power comes from its modular extension system:
| Component | Purpose |
|---|---|
| CLAUDE.md | Project-specific instructions loaded automatically at session start |
| Skills | On-demand knowledge that activates when relevant (SKILL.md files) |
| Subagents | Specialized AI workers with scoped tools and permissions |
| Hooks | Shell commands triggered at lifecycle events (PreToolUse, PostToolUse, Stop) |
| Slash commands | User-invoked shortcuts in .claude/commands/ |
| MCP servers | External tool integration (Playwright, Linear, databases) |
| Plugins | Bundled distributions of skills + commands + hooks |
vs Cursor vs Copilot
Claude Code: Terminal-first delegation. Best for autonomous task completion, background refactoring, large migrations. You describe, walk away, review results.
Cursor: IDE-native AI. Best for āflow stateā coding where you want inline edits while typing. Claude sees what you see and makes changes directly.
Copilot: Inline completions. Best for accelerating writing when you know what you want. Pattern completion and boilerplate generation.
Common pattern: Use Cursor for day-to-day editing, Claude Code for heavy-lifting (documentation, test suites, refactors). Complementary, not competing.
CLAUDE.md Best Practices
- Less is more: Every instruction competes for context window space
- Progressive disclosure: Keep task-specific instructions in separate markdown files
- Let /init generate it: Claude examines your codebase and creates tailored configuration
- Hierarchy: Root CLAUDE.md for project-wide rules, nested files for subdirectory context
Context Window Management
MCP servers eat context. Multiple servers mean less space for reasoning. Strategies:
- Disable unused MCPs and plugins
- Scope subagents to 5 tools, not 50
- Use Rube MCP to consolidate 500+ integrations into one server
Workflow Integration
Works natively with GitHub Spec Kit for spec-driven workflows. The Ralph Wiggum loop enables fully autonomous implementation: Spec Kit provides structure, Ralph provides persistence, Claude Code executes.
2026 Developments
- Claude Cowork: Research preview extending Claude Codeās agent harness to non-coding tasks
- Claude Agent SDK: The underlying harness renamed from āClaude Code SDKā to reflect broader agent applications
- Mobile development: Cloud infrastructure enables running agents from smartphones
Installation
Requires Claude subscription (Pro, Max, Teams, Enterprise) or Console account.
npm install -g @anthropic-ai/claude-codeNative IDE extensions for VS Code, Cursor, Windsurf, and JetBrains.
When to Use Claude Code
Best for: Backend work, migrations, large refactors, test generation, documentation, architecturally clear tasks
Not ideal for: UI/design work (purple gradient problem), exploratory prototyping, ambiguous requirements
Related
- Spec Kit for structured agent workflows
- The methodology behind spec-first development
- Autonomous implementation workflow