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Lab 21.7: Peer-to-Peer Agent Hand-offs

Goal​

In this lab, you will build a Collaborative Support Duo consisting of a Sales Agent and a Tech Agent. You will learn how to use the collaborators parameter to allow these agents to hand off the conversation to each other natively, without a central coordinator.

The Scenario​

  • User starts by talking to the Sales Agent.
  • If the user asks a technical question, the Sales Agent hands off to the Tech Agent.
  • If the Tech Agent hears a question about pricing or buying, it hands off back to the Sales Agent.

Step 1: Create the Project​

  1. Create a new project: 
    uv run adk create collaborative_duo

Step 2: Define the Collaborative Agents​

Open agent.py. You need to define two agents that refer to each other.

Exercise: Complete the collaborators list and instructions for both agents.

# In agent.py (Starter Code)
from google.adk import Agent

# Note: We define them with placeholder collaborator lists first 
# to avoid 'name not defined' errors in Python.

# 1. Define the Tech Agent
tech_agent = Agent(
    name="tech_agent",
    model="gemini-3.5-flash",
    description="Expert in hardware specs and troubleshooting.",
    instruction="""
    You are a technical support expert. 
    - If the user asks about prices, discounts, or how to buy, 
      you MUST hand off to the sales_agent.
    """
)

# 2. Define the Sales Agent
sales_agent = Agent(
    name="sales_agent",
    model="gemini-3.5-flash",
    description="Expert in pricing, bundles, and purchase orders.",
    instruction="""
    You are a sales representative.
    - If the user asks about hardware specs or technical issues, 
      you MUST hand off to the tech_agent.
    """,
    # TODO: Add tech_agent to collaborators
    collaborators=[] 
)

# 3. Retroactively add collaborators to tech_agent
# tech_agent.collaborators = [sales_agent]

# 4. Define the Root Agent
# In a collaborative setup, any agent can be the entry point.
root_agent = sales_agent

Step 3: Test the Hand-off​

  1. Launch the Dev UI:

    uv run adk web .

  2. Verify the Dynamic Handoff:

    • Ask: "How much does the Pro model cost?" -> Sales should answer.
    • Follow up: "Does it support 5G?" -> Sales should hand off to Tech.
    • Follow up: "Great, I'll take two. What's the discount?" -> Tech should hand off back to Sales.

  3. Inspect the Trace: In the Dev UI, look at how the active_agent changes in the trace without any manual routing code.

Lab Summary​

You have implemented a Collaborative Workflow!

  • You learned how to use the collaborators parameter.
  • You observed Native Hand-offs in action.
  • You realized that agents can act as peers, sharing responsibility for the user's session.

Self-Reflection Questions​

  • What is the main difference between a Collaborative Workflow and a Coordinator Agent?
  • Why is it necessary to assign collaborators retroactively in Python when dealing with circular references?
  • Can you think of an enterprise scenario where peer-to-peer hand-offs are safer than a central router?

🕵️ Hidden Solution 🕵️​

Looking for the solution? Here's a hint (Base64 decode me): L2RvYy1hZGstdHJhaW5pbmcvbW9kdWxlMjFfNy1jb2xsYWJvcmF0aXZlLXdvcmtmbG93cy9sYWItc29sdXRpb24=

The direct link is: Lab Solution