Node Types Overview

Overview

Flow agents use nodes as building blocks to create sophisticated conversation workflows. Each node type serves a specific purpose, and understanding when to use each type is key to building effective flows.

All Node Types at a Glance

Node Type	Primary Purpose	Key Features	Common Use Cases
Start Node	Flow entry point	Dual mode: conversation or tool	Initial greeting, pre-fetch data
Conversation Node	Natural dialogue	Variable extraction, DTMF capture	Collect info, ask questions, explain
Tool Node	Execute tool templates	Parameter mapping, error handling	API calls, database lookups
Web Tool Node	Client-side browser tools	Runs in user’s browser via SDK	UI navigation, page interactions
Router Node	Conditional branching	Pure logic, no conversation	Route based on data, decision trees
Transfer Call Node	Phone transfer	Warm/cold transfer to number	Escalate to human, department routing
Transfer Agent Node	Agent handoff	Switch to different Hamsa agent	Specialist routing, language switching
End Call Node	Terminate call	Final message, graceful exit	Completion, timeout, error handling
Set Local Variables	Set variable values	Assign static or computed values	Initialize data, transform values
Change Agent Settings	Modify agent config	Change settings mid-conversation	Switch voice, adjust behavior

Start Node

Purpose: Entry point for every flow. The first node executed when a call begins.

Two Operating Modes

Conversation Mode (Default)

Greets the caller and initiates dialogue.

Start Node (Conversation):
  message: "Thank you for calling Acme Corp. How can I help you today?"
  messageType: prompt

  Transitions:
    - Natural Language: "User needs sales" → Sales_Department
    - Natural Language: "User needs support" → Support_Department
    - DTMF: key=1 → Sales_Department
    - DTMF: key=2 → Support_Department

Tool Mode

Executes a tool before any conversation, useful for pre-fetching caller data.

Start Node (Tool):
  subType: tool
  tool: Lookup_Caller_Info
  parameters:
    phone_number: { { caller_id } }

  Transitions:
    - Always → Personalized_Greeting

When to use:

Conversation mode: Standard flows that start with a greeting
Tool mode: Pre-fetch customer data, check account status, log call start

→ Full Documentation: Start Node

Conversation Node

Purpose: The workhorse of flow agents. Used for natural dialogue with users.

Key Capabilities

Dynamic or static messages: AI-generated responses or fixed scripts
Variable extraction: Automatically capture data from conversation
DTMF input capture: Collect account numbers, PINs, phone numbers
Skip response mode: Speak without waiting for user input
Block interruptions: Prevent users from interrupting critical messages

Example - Information Gathering:

Conversation Node: Collect_Contact_Info
  messageType: prompt
  message: |
    Ask the user for their name, email, and phone number.
    Be friendly and explain we need this for follow-up.

  Variable Extraction:
    - customer_name: "Extract full name"
    - customer_email: "Extract email address"
    - customer_phone: "Extract 10-digit phone"

  Transitions:
    - Natural Language: "All info collected" → Next_Step
    - Natural Language: "User declined" → Objection_Handler

When to use:

Greeting callers
Asking questions and collecting information
Providing explanations or instructions
Handling objections
Conducting surveys
Confirming understanding

→ Full Documentation: Conversation Node

Tool Node

Purpose: Execute reusable tool templates (API Request tools, MCP tools, Function tools).

Key Features

Parameter mapping: Map variables to tool inputs
Error handling: Continue, retry, or fail on errors
Custom responses: Override default tool responses
Output mapping: Extract data from responses into variables
Processing messages: Display messages while tool executes
Timeout configuration: Set max execution time

Example - Customer Lookup:

Tool Node: Lookup_Customer
  tool: CRM_Customer_Lookup

  Parameters:
    phone_number: {{caller_phone}}
    include_orders: true

  Output Mapping:
    customer_id: $.data.id
    customer_name: $.data.full_name
    account_status: $.data.status

  Error Handling:
    onErrorBehavior: continue
    errorMessage: "I'm having trouble accessing your account right now."

  Processing Message:
    message: "Let me look up your account information..."
    messageType: static

  Transitions:
    - Equation: {{account_status}} == "active" → Active_Flow
    - Equation: {{account_status}} == "suspended" → Suspended_Flow
    - Always → Default_Flow

When to use:

Database lookups
API integrations
Check availability, status, or inventory
Submit forms or create records
Retrieve customer data
Process payments
Send notifications

→ Full Documentation: Tool Node

Web Tool Node

Purpose: Make one-off HTTP requests without creating a reusable tool template.

Key Features

Inline configuration: Define HTTP request directly in the node
No template needed: Perfect for single-use API calls
Same capabilities as Tool Node: Parameters, error handling, output mapping
Rapid prototyping: Test integrations before creating templates

Example - Weather API (One-off):

Web Tool Node: Check_Weather
  method: GET
  url: https://api.weather.com/v1/current

  Query Parameters:
    city: {{user_city}}
    units: imperial

  Headers:
    X-API-Key: {{env.WEATHER_API_KEY}}

  Output Mapping:
    temperature: $.current.temp
    conditions: $.current.conditions

  Custom Response:
    overrideResponse: true
    customResponse: "It's currently {{temperature}} degrees with {{conditions}}."

  Transitions:
    - Always → Continue_Conversation

When to use:

Quick one-off integrations
Prototyping before creating tool templates
Flow-specific API calls unlikely to be reused
Testing API endpoints
Simple GET requests

When NOT to use:

Tools needed across multiple agents (create a template instead)
Complex error handling requirements
Tools requiring extensive documentation

→ Full Documentation: Web Tool Node

Router Node

Purpose: Pure conditional routing based on variables and equations—no conversation.

Key Features

No conversation: Instantly evaluates and transitions
Multiple conditions: Complex decision trees with AND/OR logic
Variable-based routing: Branch on extracted data
High performance: Fast evaluation, no LLM calls

Example - Lead Qualification Router:

Router Node: Qualify_Lead
  label: "Route based on budget and decision maker"

  Transitions:
    - Structured Equation (Priority 1):
        logic: all
        conditions:
          - {{budget_range}} >= 5000
          - {{is_decision_maker}} == true
          - {{timeline}} == "immediate"
        → High_Priority_Sales

    - Structured Equation (Priority 2):
        logic: all
        conditions:
          - {{budget_range}} >= 1000
          - {{budget_range}} < 5000
        → Medium_Priority_Nurture

    - Structured Equation (Priority 3):
        logic: any
        conditions:
          - {{budget_range}} < 1000
          - {{is_decision_maker}} == false
        → Low_Priority_Followup

    - Always → Default_Path

When to use:

Route based on extracted variables
Implement business logic
Create decision trees
A/B test different conversation paths
Route by time of day, caller type, account status
Split flows based on data (not conversation content)

When NOT to use:

When conversation is needed to determine next step (use conversation node instead)
Simple single-condition routing (use conversation node with natural language transition)

→ Full Documentation: Router Node

Transfer Call Node

Purpose: Transfer the phone call to another phone number.

Key Features

Warm transfer: Announce transfer before connecting
Cold transfer: Immediate transfer without announcement
Transfer message: Customizable pre-transfer message
Phone number validation: E.164 format required
Timeout configuration: Set max wait time

Example - Transfer to Sales Team:

Transfer Call Node: Transfer_To_Sales
  phoneNumber: +18005551234
  transferType: warm

  Transfer Message:
    message: "Let me connect you with our sales team who can better assist you."
    messageType: static

  Timeout: 30000  # 30 seconds

Example - Emergency Transfer (Global):

Transfer Call Node: Emergency_Transfer
  isGlobal: true
  globalConditionType: dtmf
  globalDtmfKey: 0

  phoneNumber: +18005550911
  transferType: cold

  Transfer Message:
    message: "Transferring you to a specialist now."

When to use:

Escalate to human agents
Department-specific routing
After-hours transfer to answering service
Emergency or high-priority scenarios
Specialized support requiring human interaction

When NOT to use:

Transferring to another Hamsa agent (use Transfer Agent Node instead for better experience)
When conversation can continue with AI

→ Full Documentation: Transfer Call Node

Transfer Agent Node

Purpose: Transfer to another Hamsa agent while maintaining conversation context.

Key Features

Lower latency: No phone transfer needed
Context preservation: Full conversation history passed
Better reliability: No call quality issues
No repeated questions: New agent has full context
Seamless experience: User doesn’t realize they switched agents

Example - Language Switch:

Transfer Agent Node: Switch_To_Spanish
  agentId: "spanish-support-agent-id"

  Transfer Message:
    message: "Let me connect you with our Spanish-speaking representative."
    messageType: static

  Timeout: 30000

Example - Specialist Routing:

Conversation Node: Identify_Need
  message: "Are you calling about technical support or billing?"

  Transitions:
    - Natural Language: "Technical issue" → Transfer_To_Tech
    - Natural Language: "Billing question" → Transfer_To_Billing

Transfer Agent Node: Transfer_To_Tech
  agentId: "technical-support-agent"
  transferMessage: "Let me connect you with our technical specialist."

Transfer Agent Node: Transfer_To_Billing
  agentId: "billing-support-agent"
  transferMessage: "Let me connect you with our billing department."

When to use:

Route to specialized agents (tech support, billing, sales)
Language switching (English → Spanish → Mandarin)
Complexity escalation (simple → advanced agent)
Department routing within your AI system
Workflow hand-offs (qualification → closing)

Advantages over Transfer Call Node:

Faster: No phone system involved
Smarter: New agent has full context
Cheaper: No telephony transfer costs
Better UX: No hold music or reconnection

→ Full Documentation: Transfer Agent Node

End Call Node

Purpose: Gracefully terminate the conversation.

Key Features

Final message: Optional goodbye message
Call reason tracking: Mark why call ended
Static or dynamic message: Fixed script or AI-generated
Clean termination: Proper call cleanup

Example - Successful Completion:

End Call Node: Call_Complete
  reason: completed

  Final Message:
    message: "Thank you for calling Acme Corp. Have a great day!"
    messageType: static

Example - Timeout Handling:

End Call Node: Timeout_End
  reason: timeout

  Final Message:
    message: "I haven't heard from you in a while. Please call back when you're ready. Goodbye!"
    messageType: static

Example - Error Termination:

End Call Node: Error_End
  reason: error

  Final Message:
    message: "I'm experiencing technical difficulties. Please try calling back in a few minutes."
    messageType: static

When to use:

Successfully completed conversations
User requested to end call
Timeout scenarios (no user input)
Error scenarios requiring termination
After transfer (to ensure original call ends)

Reason Types:

completed: Normal completion
user_requested: User asked to end call
error: System error occurred
timeout: User inactive too long

→ Full Documentation: End Call Node

Node Selection Guide

Decision Tree: Which Node Should I Use?

Need to start the flow?
  → START NODE

Need to have a conversation?
  → CONVERSATION NODE

Need to call an API or execute a tool?
  ├─ Using existing tool template?
  │   → TOOL NODE
  └─ One-off HTTP request?
      → WEB TOOL NODE

Need to route based on data without conversation?
  → ROUTER NODE

Need to transfer the call?
  ├─ To phone number?
  │   → TRANSFER CALL NODE
  └─ To another Hamsa agent?
      → TRANSFER AGENT NODE

Need to end the call?
  → END CALL NODE

Common Node Combinations

Pattern 1: Conversation → Tool → Conversation

Collect information, call API, discuss results.

[Conversation: Ask for account number]
  → [Tool: Lookup account]
    → [Conversation: Discuss account details]

Pattern 2: Tool → Router → Multiple Paths

Fetch data, route based on results.

[Tool: Check inventory]
  → [Router: In stock?]
    ├─ Yes → [Conversation: Proceed with order]
    └─ No → [Conversation: Suggest alternatives]

Pattern 3: Conversation → Router → Transfer/End

Qualify, route to appropriate endpoint.

[Conversation: Qualification questions]
  → [Router: Decision tree]
    ├─ High priority → [Transfer Agent: Sales specialist]
    ├─ Medium priority → [Conversation: Self-service]
    └─ Low priority → [End Call: Follow-up email]

Pattern 4: Start (Tool) → Conversation

Pre-fetch data, personalized greeting.

[Start (Tool mode): Lookup caller]
  → [Conversation: "Welcome back, {{customer_name}}!"]

Next Steps

Explore individual node types in detail:

Start Node

Flow entry point with conversation or tool mode

Conversation Node

Natural dialogue with variable extraction

Tool Node

Execute reusable tool templates

Web Tool Node

Client-side browser tools via SDK

Router Node

Conditional routing based on logic

Transfer Call Node

Transfer to phone number

Transfer Agent Node

Switch to another Hamsa agent

End Call Node

Gracefully terminate calls

Set Local Variables

Set variable values without conversation

Change Agent Settings

Override agent settings mid-flow

Learn related concepts:

Transitions

Control flow between nodes

Variables

Pass data between nodes

DTMF Features

Keypad interactions and input capture

Global Nodes

Accessible from anywhere in flow

​Overview

​All Node Types at a Glance

​Start Node

​Two Operating Modes

​Conversation Mode (Default)

​Tool Mode

​Conversation Node

​Key Capabilities

​Tool Node

​Key Features

​Web Tool Node

​Key Features

​Router Node

​Key Features

​Transfer Call Node

​Key Features

​Transfer Agent Node

​Key Features

​End Call Node

​Key Features

​Node Selection Guide

​Decision Tree: Which Node Should I Use?

​Common Node Combinations

​Pattern 1: Conversation → Tool → Conversation

​Pattern 2: Tool → Router → Multiple Paths

​Pattern 3: Conversation → Router → Transfer/End

​Pattern 4: Start (Tool) → Conversation

​Next Steps

Start Node

Conversation Node

Tool Node

Web Tool Node

Router Node

Transfer Call Node

Transfer Agent Node

End Call Node

Set Local Variables

Change Agent Settings

Transitions

Variables

DTMF Features

Global Nodes

Overview

All Node Types at a Glance

Start Node

Two Operating Modes

Conversation Mode (Default)

Tool Mode

Conversation Node

Key Capabilities

Tool Node

Key Features

Web Tool Node

Key Features

Router Node

Key Features

Transfer Call Node

Key Features

Transfer Agent Node

Key Features

End Call Node

Key Features

Node Selection Guide

Decision Tree: Which Node Should I Use?

Common Node Combinations

Pattern 1: Conversation → Tool → Conversation

Pattern 2: Tool → Router → Multiple Paths

Pattern 3: Conversation → Router → Transfer/End

Pattern 4: Start (Tool) → Conversation

Next Steps