How do I use MultiServerMCPClient instead of Claude Desktop when my MCP command requires environment variables?

[wpm]

I am trying to write a chatbot that uses MCP to interact with Elasticserver. If I want to use Claude Desktop for my client, I'd add the following to my Claude Desktop configuration.

"mcpServers": {
    "elasticsearch-mcp-server-local": {
        "command": "node",
        "args": ["./dist/index.js"],
        "env": {
            "ES_URL": "https://eslasticserach-server:443",
            "ES_API_KEY": "**********"
        }
    }
}

Instead of using Claude Desktop, I want to write a LangGraph client. I'm trying to do this with MultiServerMCPClient, because that appears to be the preferred way to go. I've written something that looks like this

    client = MultiServerMCPClient(
        {
            "elasticsearch": {
                "command": "node",
                "args": ["./dist/index.js"],
                "transport": "stdio",
            }
        }
    )
    tools = await client.get_tools()
    agent = create_react_agent(
        model=model,
        tools=tools,
        checkpointer=checkpointer,
        prompt=prompt,
    )

The client.get_tools() call prints the following error

Server error: [
  {
    "code": "too_small",
    "minimum": 1,
    "type": "string",
    "inclusive": true,
    "exact": false,
    "message": "Elasticsearch URL cannot be empty",
    "path": [
      "url"
    ]
  },
  {
    "validation": "url",
    "code": "invalid_string",
    "message": "Invalid Elasticsearch URL format",
    "path": [
      "url"
    ]
  }
]

And everything is hung.

It looks like I am failing to pass the ES_URL and ES_API_KEY environment variables to the server command line called by MultiServerMCPClient. This happens regardless of whether I have these environment variables set in the terminal from which I run the client script. Claude Desktop has an env section of its configuration, but there does not appear to be an equivalent for MultiServerMCPClient.

How do I write an client for this MCP server using MultiServerMCPClient?

[wpm]

Looks like you can pass in a "env" value to the MultiServerMCPClient configuration. Is that documented anywhere?