Building & Editing Agents
Create and manage reusable voice assistant templates for consistent experiences.
Planning Your Agent
Before creating an agent, consider these key design decisions:
Define Purpose & Personality
What is your agent’s role? Customer support, sales assistant, information provider? Define the personality, tone, and expertise level.
Identify Required Capabilities
What tools and integrations does your agent need? Knowledge base access, CRM integration, payment processing?
Plan Dynamic Content
What information changes between calls? Customer names, account details, product catalogs? These become template variables.
Choose Voice & Language
Select appropriate voice characteristics and language settings for your target audience.
Creating Agents
Want to dive right in? Use our Agent Quickstart to build your first agent now.
The web app and API are fully compatible. Agents created in either can be managed through both interfaces.
Using the No-Code Web App
For teams preferring visual interfaces, Ultravox provides a web-based agent builder:
When to Use the Web App:
- Rapid prototyping and experimentation
- Non-technical team members need to create agents
- Visual configuration is preferred over code
- Quick testing of voice and personality combinations
When to Use the API:
- Production deployments, CI/CD integration, and version control
- Complex template variable schemas
- Advanced tool configurations
Transitioning Between Approaches:
- Start with the web app for rapid prototyping
- Export configurations to API calls for production
- Use the web app for quick edits, API for deployment
Using the API
Create agents programmatically for full control and integration with your development workflow:
Call Template Configuration
The call template is the heart of your agent, defining all behavior and capabilities:
System Prompt
Design effective system prompts that define your agent’s personality and knowledge. Here’s an example prompt using various template variables that will be populated at call creation time using the templateContext property:
For more, see our Prompting Guide →
Voice Configuration
Choose a voice that matches your brand and audience.
Learn more in the Voices Overview →
Tool Selection and Configuration
Connect your agent to external capabilities using tools:
Dig into more in the Tools Overview →
Agent Management
Updating Agents
You can update the agent via the Ultravox web app or via the Update Agent API.
Agent changes only affect new calls. Active calls continue using the configuration they started with.
Monitoring and Analytics
Track agent performance and usage:
When to Use Advanced Features
Start Simple: Begin with mono prompts that handle your core use case in a single system prompt. This approach works well for:
- Straightforward customer support
- Information lookup
- Basic transaction flows
Add Complexity When Needed: If mono prompting isn’t sufficient for your use case, gradually add:
- Inline instructions for multi-step processes → Guiding Agents
- Call stages for completely different conversation phases → Call Stages
Don’t Over-Engineer: Resist the temptation to add complexity early. Most voice applications can be built successfully with simple agent configurations.