[BUG] Getting error 400.

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 i try to access my files or write a program, it throws the below error
API Error: 400 {"error":{"message":"{\"message\":\"tools.0.custom.defer_loading: Extra inputs are not permitted\"}.
Received Model Group=claude-sonnet-4-6\nAvailable Model Group
Fallbacks=None","type":"None","param":"None","code":"400"}}
But I'm able to have normal conversations.

What Should Happen?

It needs to work as it usually does with bash and editing accesses/

Error Messages/Logs

API Error: 400 {"error":{"message":"{\"message\":\"tools.0.custom.defer_loading: Extra inputs are not permitted\"}.
      Received Model Group=claude-sonnet-4-6\nAvailable Model Group
     Fallbacks=None","type":"None","param":"None","code":"400"}}

Steps to Reproduce

1. open claude code cli
2. ask for going through a python file or api spec in my folders

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.69 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_