[BUG] disabledMcpjsonServers disabled when listing incorrect mcp value

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 configuring disabledMcpjsonServers to the ~/.claude/settings.json with a list of MCP server, but one of the value does not match a real mcp server, then the entire configuration get ignored. As a result, all mcp servers are enabled.

Invalid configuration example:

"disabledMcpjsonServers": ["portal", "github", "asana", "unexisting"]

This issue is also silent, no logs, no warning, /doctor does not show anything.

What Should Happen?

The incorrect MCP server "unexisting" should be ignored, allowing to disable the valid ones.

Error Messages/Logs

Steps to Reproduce

1. Install some MCP servers in your claude code setup and have them enabled on projects
2. Add the configuration ``"disabledMcpjsonServers": ["your_mcp_key"]`` to your settings.json
3. Launch a new session, you should see your context window being smaller at startup than when having all mcp enabled. /mcp should also show the mcp disabled for those matching the configuration.
4. Edit the settings.json and to have this configuration: ``"disabledMcpjsonServers": ["your_mcp_key", "unexisting"]``
5. Launch a new session, the context window is maxed and all mcp servers are enabled

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.141

Platform

Google Vertex AI

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_