sub-agent-patterns

# Sub-Agents in Claude Code

**Status**: Production Ready ✅
**Last Updated**: 2026-01-14
**Source**: https://code.claude.com/docs/en/sub-agents

Sub-agents are specialized AI assistants that Claude Code can delegate tasks to. Each sub-agent has its own context window, configurable tools, and custom system prompt.

---

## Why Use Sub-Agents: Context Hygiene

The primary value of sub-agents isn't specialization—it's **keeping your main context clean**.

**Without agent** (context bloat):
```
Main context accumulates:
├─ git status output (50 lines)
├─ npm run build output (200 lines)
├─ tsc --noEmit output (100 lines)
├─ wrangler deploy output (100 lines)
├─ curl health check responses
├─ All reasoning about what to do next
└─ Context: 📈 500+ lines consumed
```

**With agent** (context hygiene):
```
Main context:
├─ "Deploy to cloudflare"
├─ [agent summary - 30 lines]
└─ Context: 📊 ~50 lines consumed

Agent context (isolated):
├─ All verbose tool outputs
├─ All intermediate reasoning
└─ Discarded after returning summary
```

**The math**: A deploy workflow runs ~10 tool calls. That's 500+ lines in main context vs 30-line summary with an agent. Over a session, this compounds dramatically.

**When this matters most**:
- Repeatable workflows (deploy, migrate, audit, review)
- Verbose tool outputs (build logs, test results, API responses)
- Multi-step operations where only the final result matters
- Long sessions where context pressure builds up

**Key insight**: Use agents for **workflows you repeat**, not just for specialization. The context savings compound over time.

---

## Built-in Sub-Agents

Claude Code includes three built-in sub-agents available out of the box:

### Explore Agent

Fast, lightweight agent optimized for **read-only** codebase exploration.

| Property | Value |
|----------|-------|
| **Model** | Haiku (fast, low-latency) |
| **Mode** | Strictly read-only |
| **Tools** | Glob, Grep, Read, Bash (read-only: ls, git status, git log, git diff, find,