Overview
Flow Builder provides two node types for interacting with external services: the Tool/Function node for executing pre-defined tools, and the Request node for raw HTTP requests. Both integrate your flow with CRMs, booking systems, databases, and external APIs.Tool / Function Node
The Tool/Function node executes an external tool defined at the flow level. Tools are reusable API integrations with defined parameters — pre-configured API calls you can drop into any flow.Parameter Mapping
Map tool parameters to flow variables:| Tool Parameter | Mapped To |
|---|---|
customer_name | {{caller_name}} |
appointment_date | {{selected_date}} |
location_id | {{office_id}} |
Speak During Execution
API calls take time. On voice calls, silence is death. The Speak During Execution feature fills dead air:| Mode | How It Works | Best For |
|---|---|---|
| Static | Speaks fixed text (e.g., “One moment please”) | Short, predictable waits |
| Prompt | LLM generates contextual filler | Natural, personalized filler |
Sync vs Async
- Sync (default) — Flow waits for the result. Use when the next node needs the tool’s output.
- Async — Tool runs in background. Use for non-blocking tasks like logging to CRM or sending emails.
Choosing Between Tool/Function and Request Nodes
| Use Case | Recommended |
|---|---|
| Reusable integrations | Tool/Function |
| One-off API calls | Request Node |
| Need speak-during-execution | Tool/Function |
| Need fine-grained HTTP control | Request Node |
Related Pages
Request Node
Full HTTP request control
Variables
Dynamic data and substitution
Conversation Node
The core dialogue node
Engine & Streaming
How the engine processes nodes