Sub-agents

Sub-agents are specialized Claude instances that work on specific tasks in parallel with your main session.

What Are Sub-agents?

Think of sub-agents as team members you can delegate to:

Main agent (you): Architects and coordinates
Sub-agents: Handle specific tasks

Spawning Sub-agents

Use the Task tool to spawn sub-agents:

> Use a sub-agent to write tests for the auth module
> while I continue working on the API

Claude will:

Spawn a specialized agent for testing
Let you continue other work
Report back when tests are complete

Sub-agent Types

Code Review Agent

> Spawn a sub-agent to review the PR in #123
> Focus on security issues and performance

Testing Agent

> Use a sub-agent to generate comprehensive tests
> for all functions in src/utils/

Documentation Agent

> Have a sub-agent update the README and API docs
> based on recent changes

Research Agent

> Spawn a sub-agent to research best practices
> for implementing rate limiting

Parallel Execution

The real power is parallelization:

> In parallel:
> 1. Sub-agent A: Write unit tests for user service
> 2. Sub-agent B: Write integration tests for API
> 3. Main: I'll work on the new feature

Best Practices

Be Specific

# Less effective
> Have a sub-agent help with tests

# More effective
> Spawn a sub-agent to write Jest unit tests
> for src/services/user.ts covering:
> - createUser with valid/invalid input
> - updateUser authorization checks
> - deleteUser cascade behavior

Set Boundaries

> The sub-agent should only modify files in
> src/__tests__/ and not touch production code

Review Results

Always review sub-agent output:

> Show me what the testing sub-agent produced

When to Use Sub-agents

Task	Main Agent	Sub-agent
Core feature
Tests for feature
Documentation
Code review

Next Steps

In the next lesson, you'll learn about MCPs for integrating external tools.

Developers