[BUG] claude mcp add my_mcp_server ... settings not updated

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?

claude mcp add my_mcp_server -- "C:\Python311\python.exe" "path_to_my_server.py"
the settings file is not updated for the given existing mcp server name, yet the tool answers

C:\Users\{user}\.vscode\extensions\anthropic.claude-code-2.1.145-win32-x64\resources\native-binary>claude mcp add my_mcp_server -- "C:\Python311\python.exe" "path_to_my_server.py"
Added stdio MCP server my_mcp_server with command: C:\Python311\python.exe "path_to_my_server.py" to local config
File modified: C:\Users\{user}\.claude.json [project: C:\Users\andre\.vscode\extensions\anthropic.claude-code-2.1.145-win32-x64\resources\native-binary]

windows 10

What Should Happen?

settings file should be updated

Error Messages/Logs

Steps to Reproduce

have existing mcp server
do

claude mcp add my_mcp_server -- ...

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.145

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_