fix: MCP stdio server fail to start when passing env property

[jiashengguo]

Summary

The MCP Stdio server fails to start when env property is provided. This issue is due to a bug in the MCP TypeScript SDK.

Change Type

Please delete any irrelevant options.

• Bug fix (non-breaking change which fixes an issue)

Testing

In the librechat.yaml, add an arbitrary env property for the filesystem MCP server like below:

  filesystem:
    type: stdio
    command: npx
    args:
      - -y
      - '@modelcontextprotocol/server-filesystem'
      - /home/user/LibreChat/
    iconPath: /home/user/LibreChat/client/public/assets/logo.svg
    env:
      testenv: 'dummy'

• before:
  The filesystem server fails to start with the below error:
  error: [MCP][filesystem] Initialization failed spawn npx ENOENT
• after:
  The filesystem server successfully started:
  Secure MCP Filesystem Server running on stdio

Checklist

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• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes
• Any changes dependent on mine have been merged and published in downstream modules.