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Module 21.7: Collaborative Workflows - Native Agent Hand-offs

Theory​

In previous modules, you learned how to orchestrate agents using Coordinators (Module 16) or Deterministic Edges (Module 21.6). ADK 2.0 introduces a third, highly dynamic way for agents to work together: Collaborative Workflows.

What is a Collaborative Workflow?​

In a Collaborative Workflow, agents are not just "tools" called by an orchestrator. They are peers that can pass the conversation to each other directly using a native hand_off mechanism.

Unlike the Coordinator pattern where one agent always stays in control, Collaborative Workflows allow for a "Relay Race" style of interaction.

The collaborators Parameter​

To enable this, you use the collaborators parameter in the Agent definition. This tells the ADK that these agents are allowed to hand off control to one another.

from google.adk import Agent

# Agent A knows about Agent B
agent_a = Agent(
    name="sales_expert",
    collaborators=[agent_b],
    instruction="Handle sales queries. Hand off to tech_expert for technical details."
)

# Agent B knows about Agent A
agent_b = Agent(
    name="tech_expert",
    collaborators=[agent_a],
    instruction="Handle technical queries. Hand off to sales_expert for pricing."
)

How it works: Native Hand-offs​

When an agent is part of a collaborative group, the ADK automatically injects a hand_off_to_<agent_name> tool into its toolkit.

  1. Detection: The LLM realizes it cannot fulfill a request (e.g., a Sales agent gets a deep technical question).
  2. Invocation: The agent calls the auto-generated hand_off tool.
  3. Transition: The Workflow Runtime immediately pauses the current agent and activates the collaborator.

Why use Collaborative Workflows?​

  1. Dynamic Peer-to-Peer: Perfect for scenarios where there is no clear "boss" agent.
  2. Reduced Overhead: You don't need a middle-man "Router" agent that consumes tokens just to decide where to go.
  3. Natural Conversation: The transition is seamless for the user, as the context is preserved across hand-offs.

Key Takeaways​

  • Collaborative Workflows enable peer-to-peer agent transitions.
  • The collaborators list defines the "circle of trust" for an agent.
  • Native Hand-offs are powered by auto-generated tools managed by the Workflow Runtime.
  • Use this pattern for fluid, expert-led interactions where agents need to bounce the user back and forth based on evolving needs.