Chapter 37: Agent Teams (Experimental)

Agent teams are an experimental Claude Code feature that enables a lead agent to coordinate multiple teammate agents working in parallel. Enabled via CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1, teams share a task list and mailbox for inter-agent communication. This guide covers team setup, natural team groupings, hook events for teams, and when to use teams vs standard subagents.

Purpose: Coordinate multiple agents working in parallel on complex tasks Source: Anthropic Claude Code documentation (agent teams research preview) Status: Experimental (requires feature flag) Difficulty: Advanced Time: 1 hour to design first team

---

Overview

Agent Teams extend the subagent system (Chapter 36) by enabling a lead agent to coordinate multiple teammates working in parallel with a shared task list and mailbox system.

Key distinction:

• Subagents (current): Main conversation spawns agents via Task(). Agents can’t spawn other agents.
• Agent Teams (experimental): A lead agent coordinates teammates who work independently with inter-agent communication.

Subagents (Current):                   Agent Teams (Experimental):
  Main Conversation                      Lead Agent (main thread)
    ├── Task(agent-a)                      ├── Teammate A (parallel)
    ├── Task(agent-b)                      ├── Teammate B (parallel)
    └── Task(agent-c)                      └── Teammate C (parallel)
                                           Shared: task list + mailbox

---

Enabling Agent Teams

# Set the environment variable
export CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1

# Run Claude Code in agent mode
claude --agent

Warning: This is a research preview feature. Token usage is significantly higher because each teammate receives full context.

---

How Agent Teams Work

Lead Agent

The main thread agent acts as coordinator:

• Default mode: Lead can use tools AND coordinate teammates
• Delegate mode: Lead only coordinates, can’t use tools directly

Teammates

Independent agents that:

• Share a task list (read/write)
• Communicate via mailbox system
• Run in parallel
• Have their own context window

Communication

Agents coordinate through:

1. Shared task list: Create, claim, and complete tasks
2. Mailbox: Send messages between agents
3. Hook events: TeammateIdle and TaskCompleted for lifecycle

---

Team Definition File

Create team definitions in .claude/agent-teams/:

# Deployment Team

## Lead: deploy-agent

Coordinates the deployment pipeline.

## Teammates

### test-engineer

Runs pre-deployment tests and validates test coverage.

### monitoring-agent

Monitors logs and health checks after deployment.

## Workflow

1. Lead receives deployment request
2. test-engineer runs test suite in parallel
3. Lead deploys after tests pass
4. monitoring-agent watches logs for 10 minutes
5. Lead reports final status

---

Natural Team Groupings

Based on production patterns, these team compositions work well:

Team	Lead	Teammates	Use Case
Deployment	deploy-agent	test-engineer, monitoring-agent	Multi-step deployments
Data Integrity	database-agent	data-validator, accuracy-checker	Gap detection + healing
AI Quality	ai-agent	debug-specialist, prompt-engineer	AI pipeline debugging
Code Review	reviewer-lead	security-agent, style-checker	Comprehensive PR review

---

Hook Events for Teams

Two additional hook events support team coordination:

Hook	Trigger	Use For
TeammateIdle	Teammate finishes its task	Assign new work
TaskCompleted	Shared task marked done	Check dependencies

{
  "hooks": {
    "TeammateIdle": [
      {
        "hooks": [
          { "type": "command", "command": ".claude/hooks/team-coordinator.sh" }
        ]
      }
    ],
    "TaskCompleted": [
      {
        "hooks": [
          { "type": "command", "command": ".claude/hooks/task-tracker.sh" }
        ]
      }
    ]
  }
}

---

When to Use Teams vs Subagents

Scenario	Use Subagents	Use Teams
Simple parallel tasks	Yes	No
Tasks need inter-agent communication	No	Yes
Cost-sensitive work	Yes	No
Complex multi-phase workflows	Maybe	Yes
Single coordinator needed	Yes	Yes
Agents need to share state	No	Yes

Rule of thumb: Start with subagents. Only move to teams when you need agents to communicate with each other.

---

Token Considerations

Agent teams use significantly more tokens:

• Each teammate gets its own full context window
• Shared task list and mailbox add overhead
• Communication between agents adds turns

Cost control strategies:

• Use haiku model for simple teammates
• Set maxTurns on all team members
• Keep teams small (2-3 teammates)
• Use subagents for independent tasks, teams only for coordinated work

---

Preparing for Teams (Do Now)

Even without enabling teams, prepare your agent infrastructure:

1. Standardize agent frontmatter: Valid models, memory fields, maxTurns
2. Add monitoring hooks: SubagentStart/SubagentStop for visibility
3. Design team groupings: Document which agents work together
4. Keep agents focused: One clear responsibility per agent

This groundwork makes team adoption seamless when the feature stabilizes.

---

Previous: 36: Agents and Subagents