Claude Code - Model Configuration

In the previous chapter, we explored Claude Code’s built-in tools and permission system. Now let’s learn how to configure which AI model Claude Code uses for different tasks.

Model Aliases

Claude Code provides convenient aliases that automatically map to the latest model versions:

Using aliases ensures you automatically get the latest model versions without updating configuration.

Setting Your Model

Configure your model using one of these methods (listed by priority):

Switch models mid-session:

This temporarily changes the model for the current session only.

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/model sonnet

At Startup

Specify the model when starting Claude Code, setting the model for the entire session:

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claude --model opus

Environment Variable

Set a default model for all sessions, add to your .bashrc or .zshrc to make it permanent:

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export ANTHROPIC_MODEL=sonnet

Settings File (Lowest Priority)

Configure permanently in .claude/settings.json:

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{
  "model": "sonnet",
  "permissions": {
    "allow": [...]
  }
}

Checking Your Current Model

Two ways to verify which model you’re using:

1. Status Command

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/status

Displays your current model along with account information.

2. Status Line

Configure the status line to always show the current model (see status line configuration).

Special Model Features

The opusplan Hybrid Model

The opusplan alias provides intelligent model switching:

• Plan Mode: Uses Opus for complex reasoning and architecture
• Execution Mode: Switches to Sonnet for code generation

This combines Opus’s deep reasoning with Sonnet’s efficient execution.

For other special model features visit Claude Code Special Model Features.

Model Selection Strategy

Choose your model based on the task:

Use Sonnet for:

• Daily coding tasks
• Bug fixes
• Component creation
• Refactoring

Use Opus for:

• Complex architectural decisions
• System design
• Debugging difficult issues
• Performance optimization strategies

Use Haiku for:

• Simple file edits
• Quick searches
• Documentation updates
• Formatting fixes

Use opusplan for:

• Large features requiring planning
• System-wide changes
• Complex integrations

Best Practices

1. Start with default - Let Claude Code choose the appropriate model
2. Use sonnet for most work - Balanced performance and cost
3. Reserve opus for complexity - Use when you need deeper reasoning
4. Try opusplan for features - Combines planning depth with execution efficiency
5. Switch mid-session when needed - Use /model to adapt to task complexity
6. Monitor usage - Check /status to track which model you’re using
7. Set per-project defaults - Use settings files for project-specific requirements

For complete model configuration details and updates, see the official model configuration documentation.

By understanding model configuration, you can optimize Claude Code’s performance, cost, and capabilities for different types of tasks.