Variables

Overview

Echo’s variable system lets you write a single agent prompt that works for any customer and any call scenario. Use {{variable_name}} syntax anywhere in your system_prompt — Echo resolves the values before the call is initiated.

"Hi {{recipient_first_name}}, I'm calling from {{business_name}} about your {{appointment_type}} on {{appointment_time}}."

Built-in Variables

Echo automatically resolves these from your business account and the customer record. You never need to pass them in variables.

Variable	Source	Value
`{{business_name}}`	Business	Your business name from signup
`{{business_summary}}`	Business	Your business summary from signup
`{{industry}}`	Business	Your industry from signup
`{{recipient_name}}`	Customer	Full name (`first_name last_name`)
`{{recipient_first_name}}`	Customer	Customer’s first name
`{{message}}`	Notification request	The `message` field
`{{context}}`	Notification request	The `context` field (optional)

Custom Variables

Any {{token}} that isn’t in the built-in list must be supplied in the variables map when triggering a notification.

System prompt

"...your appointment at {{appointment_time}} with {{doctor_name}}. Tone: {{tone}}."
                               ↑ custom                  ↑ custom           ↑ custom

Notification request

{
  "customer_id": "...",
  "agent_id": "...",
  "variables": {
    "appointment_time": "Thursday March 20th at 2:00 PM",
    "doctor_name": "Dr. Patel",
    "tone": "warm and professional"
  }
}

Custom variables can be any string values you want. There’s no predefined list — anything you put in variables becomes available as {{key}} in the prompt.

Override Behavior

If a caller-provided variable and a built-in share the same name, the caller-provided value wins.

"variables": {
  "recipient_first_name": "Johnny"
}

This overrides the built-in {{recipient_first_name}} with "Johnny" for this specific call.

Missing Variables

If a {{token}} appears in the system prompt but has no corresponding value (neither built-in nor custom), the token is left as-is in the rendered prompt — which will cause the AI to read out {{token_name}} literally. To avoid this:

Check that every {{token}} in your prompt is either a built-in or included in variables
Use the prompt checklist before going to production

Variable Resolution Order

1. Built-in variables (auto-resolved from business + customer records)
2. Notification-time variables (from the "variables" map in the request)
   └── Overrides built-ins on name collision

Examples by Use Case

Appointment reminder

"variables": {
  "appointment_time": "Friday April 4th at 3:30 PM",
  "doctor_name": "Dr. Kim",
  "location": "Suite 200, 450 Medical Plaza"
}

Prompt excerpt

"Your appointment with {{doctor_name}} is on {{appointment_time}} at {{location}}."

Trial expiration warning

"variables": {
  "days_remaining": "2",
  "plan_name": "Pro",
  "upgrade_url": "app.yourcompany.com/upgrade"
}

Prompt excerpt

"Your {{plan_name}} trial ends in {{days_remaining}} days. Visit {{upgrade_url}} to keep access."

Delivery notification

"variables": {
  "order_number": "ORD-88231",
  "delivery_date": "tomorrow between 2 PM and 6 PM",
  "carrier": "FedEx"
}

Prompt excerpt

"Order {{order_number}} is out for delivery via {{carrier}}. Expected: {{delivery_date}}."

Per-call tone adjustment via context

"context": "This customer has called support twice this week. Be extra patient and apologetic."

Prompt excerpt

"Additional context for this call: {{context}}"

Getting Started

Guides

Overview

Built-in Variables

Custom Variables

Override Behavior

Missing Variables

Variable Resolution Order

Examples by Use Case

​Overview

​Built-in Variables

​Custom Variables

​Override Behavior

​Missing Variables

​Variable Resolution Order

​Examples by Use Case

Overview

Built-in Variables

Custom Variables

Override Behavior

Missing Variables

Variable Resolution Order

Examples by Use Case