Personalization | ElevenLabs Documentation

Overview

Personalization allows you to adapt your agent’s behavior for each individual user, enabling more natural and contextually relevant conversations. ElevenLabs offers multiple approaches to personalization:

Dynamic Variables - Inject runtime values into prompts and messages
Overrides - Completely replace system prompts or messages
Twilio Integration - Personalize inbound call experiences via webhooks

Personalization Methods

Dynamic Variables

Define runtime values using {{ var_name }} syntax to personalize your agent’s messages, system prompts, and tools.

Overrides

Completely replace system prompts, first messages, language, or voice settings for each conversation.

Twilio Integration

Dynamically personalize inbound Twilio calls using webhook data.

Conversation Initiation Client Data Structure

The conversation_initiation_client_data object defines what can be customized when starting a conversation:

1 {
2   "type": "conversation_initiation_client_data",
3   "conversation_config_override": {
4     "agent": {
5       "prompt": {
6         "prompt": "overriding system prompt",
7         "llm": "gpt-4o"
8       },
9       "first_message": "overriding first message",
10       "language": "en"
11     },
12     "tts": {
13       "voice_id": "voice-id-here"
14     },
15     "conversation": {
16       "text_only": false
17     }
18   },
19   "custom_llm_extra_body": {
20     "temperature": 0.7,
21     "max_tokens": 100
22   },
23   "dynamic_variables": {
24     "string_var": "text value",
25     "number_var": 1.2,
26     "integer_var": 123,
27     "boolean_var": true
28   },
29   "user_id": "your_custom_user_id",
30   "branch_id": "agtbrch_xxxx",
31   "environment": "production"
32 }

System dynamic variables (those prefixed with system__) cannot be sent or overridden in the client initiation payload. Only custom dynamic variables can be set via the dynamic_variables field.

Choosing the Right Approach

Method	Best For	Implementation
Dynamic Variables	Inserting user-specific data into templated content - Maintaining consistent agent behavior with personalized details - Personalizing tool parameters	Define variables with `{{ variable_name }}` and pass values at runtime
Overrides	Completely changing agent behavior per user - Switching languages or voices - Legacy applications (consider migrating to Dynamic Variables)	Enable specific override permissions in security settings and pass complete replacement content

Overview

Personalization Methods

Conversation Initiation Client Data Structure

Choosing the Right Approach

Learn More