CLI: `code --add-mcp <json>` strips quotes when invoked from PowerShell on Windows

[toakiryu]

CLI: code --add-mcp <json> loses quotes when invoked from PowerShell (Windows)

Summary

Invoking code --add-mcp '<json>' from PowerShell (pwsh) causes the JSON double-quotes to be stripped or mangled, leading to JSON parse errors. Running the VS Code CLI implementation (cli.js) directly with node succeeds, which suggests the issue is in the PowerShell → cmd handoff or the code wrapper's argument handling.

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Environment

• OS: Windows 11 Pro (Edition: Windows 11 Pro, Version: 24H2, OS build: 26100.6899)
• VS Code: code --version output:
  • 1.105.1
  • 7d842fb85a0275a4a8e4d7e040d2625abbf7f084
  • x64
• Shell: pwsh.exe (PowerShell/Core)
• PowerShell: 7.5.3
• Node: v22.18.0
• code executable: C:\Users\toaki\AppData\Local\Programs\Microsoft VS Code\bin\code.cmd

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Steps to reproduce (minimal)

1. Open PowerShell (pwsh).
2. Run (copy-paste):

code --add-mcp '{"name":"next-devtools","command":"pnpm","args":["dlx","next-devtools-mcp@latest"]}'

3. Expected: MCP server is added, or CLI prints a success message.
4. Actual: Error like:

Invalid JSON '{name:next-devtools,command:pnpm,args:[dlx,next-devtools-mcp@latest]}': SyntaxError: Expected property name or '}' in JSON at position 1 (line 1 column 2)

(Quotes appear to be removed before parsing.)

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Control / Workaround

Calling the CLI directly via node succeeds, showing the JSON is valid and the internal CLI can accept it:

node "C:\Users\toaki\AppData\Local\Programs\Microsoft VS Code\resources\app\out\cli.js" --add-mcp '{"name":"next-devtools","command":"pnpm","args":["dlx","next-devtools-mcp@latest"]}'

Output:

Added MCP servers: next-devtools

Temporary workarounds:

• Call cli.js directly with node as above.
• Write JSON to a temporary file and read it in PowerShell:

@'
'{"name":"next-devtools","command":"pnpm","args":["dlx","next-devtools-mcp@latest"]}
'@ > .\mcp.json
code --add-mcp (Get-Content .\mcp.json -Raw)

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Expected behavior

JSON passed from PowerShell should be forwarded intact to the code CLI and parsed successfully.

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Actual behavior

Double-quotes in JSON are removed when code is invoked from PowerShell, resulting in a parse error.

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Notes

This appears to be an argument-quoting/escaping issue when PowerShell hands arguments to the code wrapper (code.cmd) which forwards %* to Code.exe.