Prompt Library

Create reusable, dynamic prompts with Handlebars template variables and AI-assisted generation.

The Prompt Library lets you write prompts once and reference them across multiple flows. Changes to a library prompt propagate to every flow that uses it.

Creating prompts

Open the Prompt Library from the Flow Builder sidebar. Each prompt has:

Name — a descriptive identifier (e.g., "Support Agent System Prompt")
Category — optional grouping for organization
Content — the prompt text with optional Handlebars template variables

Template variables

Prompts support Handlebars syntax for injecting dynamic data at runtime. Variables are replaced with real values when the call starts.

You are a support agent for {{account.name}}.
The caller's name is {{default contact.name "there"}}.
{{#ifExists contact.company}}They work at {{contact.company}}.{{/ifExists}}

Contact variables

Variable	Type	Description
`contact.name`	string	Full name
`contact.firstName`	string	First name (derived)
`contact.lastName`	string	Last name (derived)
`contact.primaryPhone`	string	Phone number
`contact.email`	string	Email address
`contact.company`	string	Company name
`contact.occupation`	string	Job title
`contact.notes`	string	Free text notes
`contact.timezone`	string	Timezone (e.g., "America/New_York")
`contact.language`	string	Language code (e.g., "en")
`contact.interests`	array	Topics and hobbies
`contact.personality`	array	Personality traits
`contact.communicationStyle`	string	Communication style
`contact.preferredTopics`	array	Preferred discussion topics
`contact.tags`	array	Labels and tags
`contact.address.street`	string	Street address
`contact.address.city`	string	City
`contact.address.state`	string	State/province
`contact.address.postalCode`	string	ZIP/postal code
`contact.address.country`	string	Country
`contact.customFields`	object	Any custom fields you've defined

Call variables

Variable	Type	Description
`call.id`	string	Call UUID
`call.direction`	string	`inbound` or `outbound`
`call.fromNumber`	string	Caller ID / source number
`call.toNumber`	string	Destination number

Account variables

Variable	Type	Description
`account.id`	string	Account UUID
`account.name`	string	Account name

System variables

Always available, populated automatically.

Variable	Type	Description
`system.date`	string	Current date (YYYY-MM-DD)
`system.time`	string	Current time (HH:MM:SS)
`system.timezone`	string	Timezone (default: UTC)
`system.timestamp`	string	Full ISO 8601 timestamp

Helpers

Helpers let you transform data, handle missing values, and add conditional logic inside your prompts.

default

Returns a fallback value when the variable is empty or missing.

Hello {{default contact.name "there"}}, thanks for calling {{default account.name "us"}}.

ifExists

Block helper that renders content only when the value exists and is not empty.

{{#ifExists contact.email}}We'll send a confirmation to {{contact.email}}.{{else}}Can I get your email for a confirmation?{{/ifExists}}

Comparisons

Use inside {{#if ...}} blocks. All return true/false.

Helper	Description	Example
`eq`	Equal	`{{#if (eq call.direction "inbound")}}`
`ne`	Not equal	`{{#if (ne contact.language "en")}}`
`gt`	Greater than	`{{#if (gt call.duration 300)}}`
`lt`	Less than	`{{#if (lt contact.tags.length 3)}}`
`gte`	Greater or equal	`{{#if (gte account.plan "pro")}}`
`lte`	Less or equal	`{{#if (lte retry_count 3)}}`

Logic

Combine conditions with boolean logic.

{{#if (and contact.email contact.company)}}
I see you're at {{contact.company}} — I'll send details to {{contact.email}}.
{{/if}}

{{#if (or contact.notes contact.preferredTopics)}}
I have some context about your preferences.
{{/if}}

{{#if (not contact.notes)}}
I don't have any notes on file for you.
{{/if}}

String and array

Helper	Description	Example
`includes`	Check if array contains value or string contains substring	`{{#if (includes contact.tags "vip")}}VIP treatment{{/if}}`
`match`	Regex test on a string	`{{#if (match contact.primaryPhone "^\\+1")}}US number{{/if}}`
`replace`	Regex replace (global)	`{{replace contact.primaryPhone "[^0-9]" ""}}`
`join`	Join array elements with separator	`{{join contact.interests ", "}}`
`json`	Convert value to JSON string	`{{json contact.address}}`

formatDate

Format ISO 8601 date strings.

Today is {{formatDate system.date "long"}}.

Format	Output
`"short"`	MM/DD/YYYY
`"long"`	Month DD, YYYY
`"time"`	HH:MM:SS
`"datetime"`	YYYY-MM-DD HH:MM:SS
(default)	YYYY-MM-DD

Behavior

Missing variables render as empty — strict mode is off, so an undefined variable won't crash the call
No HTML escaping — output is plain text for voice, not web
Truthiness — empty strings, "none", "null", empty arrays, and empty objects are all treated as falsy

AI-assisted generation

Click Generate to describe what you want in plain language. The AI creates a complete Handlebars template using your available variables.

The generator knows about your contact fields, call context, and all available helpers. It produces prompts that are immediately usable — no placeholder text, no manual editing required.

Multi-turn chat is supported. Refine the generated prompt by asking for changes in follow-up messages.

Using prompts in agent nodes

When configuring an Agent node's system prompt or task prompt, you can either:

Write inline — type the prompt directly in the agent node
Reference a library prompt — select from the Prompt Library dropdown

Library prompts appear with a link icon in the agent node, indicating the prompt is managed centrally.

Best practices

Use the library for prompts shared across multiple flows (e.g., company-wide tone guidelines)
Use inline prompts for flow-specific instructions that won't be reused
Use default for every contact field — not all contacts have complete data
Use ifExists blocks to conditionally include entire sections
Adapt behavior based on call.direction — inbound and outbound calls need different openings
Keep prompts focused on one objective per agent node

Prompt Library

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