Use --model at Launch to Pick Your Starting Model

Most developers launch Claude Code and let it default to whatever model is configured globally. You can be more intentional by specifying the model at the start of each session:

# Start a focused session on Sonnet for implementation work
claude --model claude-sonnet-4-6

# Start on Opus for an architecture investigation
claude --model claude-opus-4-6

# Short form also works
claude -m sonnet

Pair this with /model mid-session to shift gears as the task changes. Start on Opus for planning, switch to Sonnet for the execution phase once the approach is clear.

For one-off tasks where you know the model upfront, set it in the command:

# Quick code generation task — Sonnet is fine, no need for Opus
claude --model sonnet -p "Add a created_at timestamp to every model that doesn't have one"

To avoid specifying it every time, set a default in your settings:

// ~/.claude/settings.json
{
  "model": "claude-sonnet-4-6"
}

Or use the environment variable, which is useful in CI:

ANTHROPIC_MODEL=claude-sonnet-4-6 claude -p "Run the test suite and fix any failures"

Pick the right model at launch — you'll spend less and lose nothing on routine tasks.