Kiro provides two powerful AI agent options to handle your development tasks: Auto and Claude Sonnet 4.0. Each offers distinct advantages depending on your needs and usage patterns.
Available models
Auto (Recommended)
Auto is Kiro's default intelligent model router that combines multiple frontier models with advanced optimization techniques.
Key benefits:
- Cost-effective – Approximately 23% less expensive than direct Sonnet 4 usage
- Smart routing – Automatically chooses the optimal model for each task
- Consistent quality – Delivers Sonnet 4-level results across different task types
- Plan efficiency – Makes your usage limits go further
What model does Auto use?
Auto uses best in class LLM models (Claude Sonnet 4 and alike) to provide you the best quality for the type of tasks assigned to the agent. We maintain a very high bar to ensure that the quality of what is offered under Auto compares to or exceeds the quality of separate models made available to our users.
Claude Sonnet 4.0
Direct access to Anthropic's Claude Sonnet 4.0 model for users who prefer consistent model selection or have specific requirements for using this particular model.
Key benefits:
- Predictable behavior – Same model for all interactions
- Direct access – No routing or optimization layers
- Full control – Complete transparency in model selection
Cost comparison
Understanding the credit consumption differences:
| Model | Credit Usage | Example Task Cost |
|---|---|---|
| Auto | 1.0x | 10 credits |
| Sonnet 4.0 | 1.3x | 13 credits |
Choosing the right model
Auto
Consider using Auto when:
- Cost efficiency matters – You want to maximize your plan's value
- General development work – Most coding, debugging, and planning tasks
- Variable task types – Working on diverse projects with different requirements
- Plan optimization – You want your limits to stretch further
Sonnet 4.0
Consider using Sonnet 4.0 when:
- Consistency is critical – You need predictable model behavior
- Specific requirements – Your workflow depends on Sonnet 4's particular capabilities
- Model transparency – You prefer knowing exactly which model handles each request
- Budget flexibility – Higher costs aren't a primary concern
How to switch models
In the chat interface
-
Access model selector
- Look for the model dropdown in the chat interface
- Default selection is "Auto"
-
Choose your model
- Select "Auto" for intelligent routing
- Select "Claude Sonnet 4.0" for direct access
-
Confirmation
- Your selection applies to subsequent messages
- Current conversation context is maintained
Best practices
Maximizing efficiency
- Start with Auto – Use it as your default for most tasks
- Monitor usage – Track how different models affect your plan consumption
- Switch strategically – Use Sonnet 4 for specific high-stakes tasks
- Experiment – Try both models for similar tasks to compare results
Cost management
- Plan accordingly – Factor model choice into your tier selection
- Track patterns – Understand which tasks benefit most from each model
- Optimize workflows – Adjust development practices based on model strengths
- Consider overages – Enable if you need flexibility beyond plan limits
Model Selection