Windows requires cmd /c wrapper for npx in .claude.json MCP servers

[ipoweb]

Description

When running Claude Code (SuperClaude) on Windows, the current default .claude.json configuration for MCP servers uses:

"command": "npx"

This works fine on Linux/macOS, but on Windows it triggers warnings like:

Windows requires 'cmd /c' wrapper to execute npx

and prevents MCP servers (such as sequential-thinking, context7, magic, playwright, morphllm-fast-apply) from starting correctly.

Steps to Reproduce

Install and run Claude Code on Windows 10/11.

Use a .claude.json with MCP servers defined like this:

"sequential-thinking": {
  "type": "stdio",
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-sequential-thinking"]
}

Launch Claude Code.

Actual Behavior

Warnings appear in the logs:

[Warning] [sequential-thinking] mcpServers.sequential-thinking: Windows requires 'cmd /c' wrapper to execute npx

The MCP servers do not run properly.

Expected Behavior

The configuration should work out-of-the-box on Windows, without requiring manual edits to .claude.json.

Workaround

The user must manually edit .claude.json and wrap each MCP server call in cmd /c:

"sequential-thinking": {
  "type": "stdio",
  "command": "cmd",
  "args": [
    "/c",
    "npx",
    "-y",
    "@modelcontextprotocol/server-sequential-thinking"
  ]
}

This resolves the issue, but it is tedious and error-prone.

Suggested Fix

Automatically detect Windows and prepend "cmd", "/c" when executing npx.

Or provide platform-specific defaults in .claude.json.

Alternatively, update documentation with a ready-to-use Windows example config.

Environment

OS: Windows 11 Pro (x64)

Claude Code version: V1.0.124

Node.js version: 22.14

[mithun50]

I have fixed the problem and I'll close this issue for my convince if any thing else feel free to open the issue