Claude Opus over-engineers simple tasks in agentic/CLI mode, wasting tokens

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When using Claude Code with the Opus model, simple tasks trigger excessive tool calls. Asking Opus to rename a string across 3 files resulted in 15+ tool calls including reading files multiple times after writing them, creating temp files in /tmp to store grep results, and running redundant validation loops before and after every step. The same task on Sonnet completes in 2-3 tool calls.

What Should Happen?

Renaming a string across 3 files should take 5-6 tool calls: read, replace, write, validate. Opus should match tool usage to task complexity the same way Sonnet does.

Error Messages/Logs

Steps to Reproduce

Open Claude Code with Opus (/model opus)
Create any 3 text files that share a common string
Ask: "Rename the string foo to bar across these 3 files"
Observe Opus running 15+ tool calls with redundant checks, temp files, and re-reading files it just wrote
Repeat with Sonnet (/model sonnet) — same task completes in 2-3 tool calls

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Opus 4.8

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

Just try different light tasks with opus, you will see it overcomplicating things.