[BUG] Claude Opus 4.6 produces repeated malformed tool calls

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?

During a simple session (remove an h1, edit text, commit and push), Claude made ~10+ failed tool calls in a row. Errors included:

• Misspelled paths (jeongwookyam, jeongwei, agent-agentata-landing)
• Missing required parameters (empty Bash calls)
• Garbled parameter values (page.ableContentOfAlignment.tsx, Co-Authored-Byode)
• Broken XML/tool call structure

A simple git add && commit && push took many attempts before succeeding. Session date: 2026-02-09, model: claude-opus-4-6.

What Should Happen?

Should read and navigate files properly but can't spell paths right at all.

Error Messages/Logs

Steps to Reproduce

Literally all I did was to try multiple tasks

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_