MCP servers not connecting on Windows 11 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?

Description
MCP servers configured in ~/.claude/mcp.json are not being loaded/connected by Claude Code CLI on Windows 11. The MCP server works correctly when called directly via bash, but Claude Code does not recognize or connect to it.

Environment
OS: Windows 11
Node.js: v24.4.0
npm: 11.7.0
Claude Code: (run claude --version from CMD/PowerShell to get this)

What Should Happen?

Expected Behavior
/mcp should list connected servers
MCP tools should be available in Claude's toolset

Error Messages/Logs

Actual Behavior
/mcp shows empty/nothing
MCP server is not connected
No error messages displayed
Verification that MCP server works
echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' | "C:/GoWrkCode/go-w2c/w2c-ai-mcp/w2c-ai-mcp.exe" --lib "C:/GoWrkCode/go-w2c/w2c-Forms-UI-Lib-DaHerb01" --app "C:/GoWrkCode/go-w2c/w2c-forms"

Returns valid response:

{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{"listCha

Steps to Reproduce

Steps to Reproduce
Create MCP server executable (Go-based, stdio transport)
Configure ~/.claude/mcp.json as shown above
Start Claude Code CLI
Run /mcp command - shows nothing, terminal briefly opens and closes

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.1.1520

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

VS Code extension also shows MCP disabled via feature gate (logs show Gate returned: false)
Possible Windows-specific issue or feature rollout not yet enabled