[BUG] MCP tool search stopped working since some version between 2.1.67 and 2.1.71

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?

All my active MCPs are consuming my context in /context. The conversation summarizes the context on almost every interaction as a result.

Investigation shows that tool search a.k.a. ENABLE_TOOL_SEARCH=true doesn't work. Downgrading it back to 2.1.66 solves the issue, as switching ENABLE_TOOL_SEARCH shows the difference in /context.

What Should Happen?

Tool search a.k.a. ENABLE_TOOL_SEARCH=true should work and prevent MCP from consuming conversation context initially.

Error Messages/Logs

Steps to Reproduce

1. Install an MCP and activate it
2. Turn on tool search
3. Start Claude Code instance
4. Run /context to verify that each tool consumes token

This is not reproducible on 2.1.66. /context shows no MCP tools consuming tokens, and will be "loaded on-demand".

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.66

Claude Code Version

2.1.71 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

_No response_