On one hand, Opus 4 is crazy exciting. However, in API it costs about five times as much as Sonnet. I see some reports coming in that people are hitting rate limits much faster in Claude Code using Opus, which makes sense.

It looks like you can change the model that Claude Code uses. Maybe that will help preserve your limits if you do not need all that extra firepower?

Here is a link from the Anthropic website, and also Sonnet 4's How To when I asked.

https://docs.anthropic.com/en/docs/claude-code/bedrock-vertex-proxies

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For Regular Windows Users (Using Anthropic's API)

The Bedrock references are for enterprise users who want to use Amazon's cloud service instead of Anthropic's API directly. You can ignore those - here's what you need for regular Windows usage:

Option 1: Environment Variables (Windows)

Command Prompt:

set ANTHROPIC_MODEL=claude-sonnet-4-20250514
set ANTHROPIC_SMALL_FAST_MODEL=claude-3-5-haiku-20241022
claude

PowerShell:

$env:ANTHROPIC_MODEL="claude-sonnet-4-20250514"
$env:ANTHROPIC_SMALL_FAST_MODEL="claude-3-5-haiku-20241022"
claude

Option 2: Persistent Configuration (Recommended)

This is probably easier for Windows users:

claude config set -g ANTHROPIC_MODEL claude-sonnet-4-20250514
claude config set -g ANTHROPIC_SMALL_FAST_MODEL claude-3-5-haiku-20241022

This saves the configuration permanently so you don't need to set environment variables each time.

Option 3: Windows Environment Variables (System-wide)

If you want this to be permanent across all command prompt sessions:

1. Press Win + R, type sysdm.cpl, press Enter

2. Click "Environment Variables"

3. Under "User variables" click "New"

4. Variable name: ANTHROPIC_MODEL

5. Variable value: claude-sonnet-4-20250514

6. Repeat for ANTHROPIC_SMALL_FAST_MODEL with value claude-3-5-haiku-20241022 '''