Sub Agent Relationships

Sub Agent relationships are used to coordinate specialized Sub Agents for complex workflows. This framework implements Sub Agent relationships through using canDelegateTo() and canTransferTo(), allowing a parent Sub Agent to automatically coordinate specialized Sub Agents for complex workflows.

Understanding Sub Agent Relationships

The framework supports two types of Sub Agent relationships:

Transfer Relationships

Transfer relationships completely relinquish control from one Sub Agent to another. When a Sub Agent hands off to another:

The source Sub Agent stops processing
The target Sub Agent takes full control of the conversation
Control is permanently transferred until the target Sub Agent hands back

import { subAgent, agent } from "agent-sdk";

// Create specialized Sub Agents first
const qaSubAgent = subAgent({
  id: "qa-agent",
  name: "QA Sub Agent",
  description: "Answers product and service questions",
  prompt: "Provide accurate information using available tools. Hand back to router if unable to help.",
  canUse: () => [knowledgeBaseTool],
  canTransferTo: () => [routerSubAgent],
});

const orderSubAgent = subAgent({
  id: "order-agent",
  name: "Order Sub Agent",
  description: "Handles order-related inquiries and actions",
  prompt: "Assist with order tracking, modifications, and management.",
  canUse: () => [orderSystemTool],
  canTransferTo: () => [routerSubAgent],
});

// Create router Sub Agent that coordinates other Sub Agents
const routerSubAgent = subAgent({
  id: "router-agent",
  name: "Router Sub Agent",
  description: "Routes customer inquiries to specialized Sub Agents",
  prompt: `Analyze customer inquiries and route them appropriately:
    - Product questions → Hand off to QA Sub Agent
    - Order issues → Hand off to Order Sub Agent
    - Complex issues → Handle directly or escalate`,
  canTransferTo: () => [qaSubAgent, orderSubAgent],
});

// Create the agent with router as default entry point
const supportAgent = agent({
  id: "customer-support-agent",
  defaultSubAgent: routerSubAgent,
  subAgents: () => [routerSubAgent, qaSubAgent, orderSubAgent],
  models: {
    base: {
      model: "anthropic/claude-sonnet-4-5",
      providerOptions: {
        temperature: 0.5,
      },
    },
    structuredOutput: {
      model: "openai/gpt-4.1-mini",
    },
  },
});

Delegation Relationships

Delegation relationships are used to pass a task from one Sub Agent to another while maintaining oversight:

The source Sub Agent remains in control
The target Sub Agent executes a specific task
Results are returned to the source Sub Agent
The source Sub Agent continues processing

// Sub Agents for specific tasks
const numberProducerA = subAgent({
  id: "number-producer-a",
  name: "Number Producer A",
  description: "Produces low-range numbers (0-50)",
  prompt: "Generate numbers between 0 and 50. Respond with a single integer.",
});

const numberProducerB = subAgent({
  id: "number-producer-b",
  name: "Number Producer B",
  description: "Produces high-range numbers (50-100)",
  prompt: "Generate numbers between 50 and 100. Respond with a single integer.",
});

// Coordinating Sub Agent that delegates tasks
const mathSupervisor = subAgent({
  id: "math-supervisor",
  name: "Math Supervisor",
  description: "Coordinates mathematical operations",
  prompt: `When given a math task:
    1. Delegate to Number Producer A for a low number
    2. Delegate to Number Producer B for a high number
    3. Add the results together and provide the final answer`,
  canDelegateTo: () => [numberProducerA, numberProducerB],
});

const mathAgent = agent({
  id: "math-delegation-agent",
  defaultSubAgent: mathSupervisor,
  subAgents: () => [mathSupervisor, numberProducerA, numberProducerB],
  models: {
    base: {
      model: "anthropic/claude-haiku-4-5",
      providerOptions: {
        temperature: 0.1,
      }
    }
  },
});

When to Use Each Relationship

Use Transfers for Complex Tasks

Use canTransferTo when the task is complex and the user will likely want to ask follow-up questions to the specialized Sub Agent:

Customer support conversations - User may have multiple related questions
Technical troubleshooting - Requires back-and-forth interaction
Order management - User might want to modify, track, or ask about multiple aspects
Product consultations - Users often have follow-up questions

Use Delegation for Simple Tasks

Use canDelegateTo when the task is simple and self-contained:

Data retrieval - Get a specific piece of information and return it
Calculations - Perform a computation and return the result
Single API calls - Make one external request and return the data
Simple transformations - Convert data from one format to another

// TRANSFER: User will likely have follow-up questions about their order
const routerSubAgent = subAgent({
  id: "router",
  prompt: "For order inquiries, transfer to order specialist",
  canTransferTo: () => [orderSubAgent],
});

// DELEGATION: Just need a quick calculation, then continue
const mathSupervisor = subAgent({
  id: "supervisor",
  prompt: "Delegate to number producers, then add results together",
  canDelegateTo: () => [numberProducerA, numberProducerB],
});

import { myExternalAgent } from "./external-agents/external-agent-example";

const mathSupervisor = subAgent({
  id: "supervisor",
  prompt: "Delegate to the external agent to calculate the answer to the question",
  canDelegateTo: () => [myExternalAgent],
});

You can also specify headers to include with every request to the external agent.

const mathSupervisor = subAgent({
  id: "supervisor",
  prompt: "Delegate to the external agent to calculate the answer to the question",
  canDelegateTo: () => [myExternalAgent.with({ headers: { "authorization": "my-api-key" } })],
});

Team Agent Delegation

Team agent delegation is used to delegate a task to another agent in the same project.

import { myAgent } from "./agents/my-team-agent";

const mathSupervisor = subAgent({
  id: "supervisor",
  prompt: "Delegate to the team agent to calculate the answer to the question",
  canDelegateTo: () => [myAgent],
});

You can also specify headers to include with every request to the team agent.

const mathSupervisor = subAgent({
  id: "supervisor",
  prompt: "Delegate to the team agent to calculate the answer to the question",
  canDelegateTo: () => [myAgent.with({ headers: { "authorization": "my-api-key" } })],
});

Understanding Sub Agent Relationships

Transfer Relationships

Delegation Relationships

When to Use Each Relationship

Use Transfers for Complex Tasks

Use Delegation for Simple Tasks

Types of Delegation Relationships

Sub Agent Delegation

External Agent Delegation

Team Agent Delegation

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