Tool & Function Nodes

Overview

Flow Builder provides two node types for interacting with external services: the Tool/Function node for executing pre-defined tools, and the Request (API Call) node for making raw HTTP requests. Both let you integrate your flow with CRMs, booking systems, databases, and any external API.

Tool / Function Node

The Tool/Function node executes an external tool that's been defined at the flow level. Tools are reusable API integrations with defined parameters — think of them as pre-configured API calls that you can drop into any flow.

Parameter Mapping

Each tool has defined parameters (e.g., customer_name, appointment_date). In the node configuration, you map these parameters to flow variables:

Tool Parameter	Mapped To
customer_name	{{caller_name}}
appointment_date	{{selected_date}}
location_id	{{office_id}}

When the node executes, the variable values are substituted into the tool parameters before the API call is made.

Speak During Execution

API calls take time. On a voice call, silence is death. The Speak During Execution feature fills dead air while the tool runs:

Mode	How It Works	Best For
Static	Speaks a fixed text you define (e.g., "One moment please")	Short, predictable waits
Prompt	LLM generates contextual filler based on a prompt (e.g., "Let me look up those appointment times for you, Sarah!")	Natural, personalized filler

Tip: Prompt-mode filler adds a small LLM call, but the result sounds much more natural on voice. Use static mode when speed is more important than personality.

Sync vs Async Execution

By default, Tool/Function nodes execute synchronously — the flow waits for the result before continuing. Enable the async flag to run the tool in the background while the conversation continues.

Use async for non-blocking tasks like:

• Logging data to a CRM
• Sending confirmation emails
• Updating external databases

Use sync when the next node needs the tool's result (e.g., looking up appointment availability before presenting options).

Edge Handles

Handle	Position	Color	Purpose
Input	Top	Blue	Receives connections
Output	Right	Standard	Next node after execution completes
Async	Bottom	Yellow	Nodes to run in parallel

Request (API Call) Node

The Request node gives you full control over an HTTP request — method, URL, headers, authentication, query parameters, and body. Use it when you need precise control over an API call that doesn't fit a pre-defined tool.

Configuration

Field	Description
method	HTTP method: GET, POST, PUT, PATCH, DELETE
url	Full URL — supports {{variable}} substitution
contentType	Content-Type header value
authorization	Authorization header (e.g., Bearer {{api_token}})
headers[]	Additional headers as key-value pairs
queryParams[]	URL query parameters as key-value pairs
bodyMode	key-value (form params) or raw (JSON/text body)
bodyParams[]	Body parameters when using key-value mode
body	Raw body content when using raw mode
responseVariable	Variable name to store the response
await	Whether to wait for the response before continuing

All fields that accept text also support {{variable}} substitution — URLs, headers, body, query params, everything.

Response Variables

When you set a responseVariable (e.g., booking_result), the node creates three variables:

Variable	Contains
{{booking_result}}	The response body (parsed JSON or text)
{{booking_result_status}}	HTTP status code (e.g., 200, 404)
{{booking_result_error}}	Error message if the request failed

Timeout

Request nodes have a 10-second timeout. If the external API doesn't respond in time, the request fails and the error variable is populated.

Edge Handles

Handle	Position	Color	Purpose
Input	Top	Blue	Receives connections
Output	Right	Standard	Next node after request completes
Async	Bottom	Yellow	Nodes to run in parallel

Choosing Between Tool/Function and Request Nodes

Use Case	Recommended Node
Reusable integrations used across flows	Tool/Function
One-off API calls specific to a flow	Request
Need speak-during-execution filler	Tool/Function
Need fine-grained HTTP control	Request
Dynamic URL / header construction	Request