[BUG] API Error: 400 tools.0.custom.defer_loading: Extra inputs are not permitted on every request in v2.1.69

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?

Every request in Claude Code v2.1.69 fails immediately with:
API Error: 400 tools.0.custom.defer_loading: Extra inputs are not permitted
The error occurs on every request regardless of content — even a simple "hello" triggers it.

What Should Happen?

The message should be processed normally.

Error Messages/Logs

API Error: 400 tools.0.custom.defer_loading: Extra inputs are not permitted

Steps to Reproduce

1. Install or update to Claude Code 2.1.69
2. Start a new session: claude
3. Type any message (e.g., hello)
4. Observe the 400 error

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.68

Claude Code Version

2.1.69 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_