Unable to disable Claude_in_Chrome and Claude_Preview despite correct configuration

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?

Summary

I'm unable to disable the built-in Claude_in_Chrome and Claude_Preview MCP servers, even with proper configuration in both settings files and a fresh restart of Claude Code.

Environment

• Claude Code Version: [Check: About Claude Code]
• Operating System: macOS [your version, e.g., macOS 14.2]
• Browser: Chrome (for Claude_in_Chrome reference)

Configuration Applied

~/.claude/settings.json

{
  "disabledMcpjsonServers": [
    "Claude_in_Chrome",
    "Claude_Preview"
  ]
}
~/.claude.json (project-level)
For each project in the projects section:

"disabledMcpServers": [
  "Claude_in_Chrome",
  "Claude_Preview"
]


### What Should Happen?

Expected Behavior
Claude_in_Chrome and Claude_Preview should NOT appear in the loaded MCP tools list.

Actual Behavior
Both Claude_in_Chrome and Claude_Preview continue to load and appear in the context window (consuming ~30k tokens), despite being listed in disabledMcpServers / disabledMcpjsonServers.

Related Issues
This appears related to:

#13311 - "Bug: disabledMcpServers setting not enforced at session startup"
#37284 - "Desktop: No way to prevent built-in MCP servers from being injected into Code tab sessions"
Additional Context
I've verified that the field names match the settings.json schema exactly. The configuration is syntactically correct and validated without errors. The issue persists across multiple restarts and new sessions.

### Error Messages/Logs

```shell

Steps to Reproduce

Steps to Reproduce
Configure disabledMcpjsonServers in ~/.claude/settings.json
Configure disabledMcpServers in ~/.claude.json projects section
Restart Claude Code completely (force quit if necessary)
Start a new session
Run /context command to check loaded MCP tools

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.123

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_