Run Subagents on a Cheaper Model to Cut Costs

Subagents handle scoped tasks like file searches, research, and code analysis. They don’t need the full power of Opus, so route them to Sonnet for significant savings.

Setup

# In your shell profile (.zshrc, .bashrc)
export CLAUDE_CODE_SUBAGENT_MODEL="claude-sonnet-4-6"

Now your main session uses Opus for complex reasoning while subagents use Sonnet for research, exploration, and validation tasks.

Other Cost Environment Variables

# Suppress background token usage (suggestions, tips)
export DISABLE_NON_ESSENTIAL_MODEL_CALLS=1

# Control reasoning effort (low/medium/high/max/auto)
export CLAUDE_CODE_EFFORT_LEVEL=medium

When to Use

• Long sessions with many subagent calls, where the savings compound
• Research-heavy tasks where subagents do file exploration
• CI/CD pipelines where you’re paying per token

When NOT to Use

• When subagent tasks require complex multi-step reasoning
• When subagents need to make nuanced architectural decisions
• If you notice subagent quality dropping, upgrade back to Opus