[BUG] Environment variables in MCP Servers configuration seems to not be passed/used correctly

[matteo-ladrat-Legrand]

Context

I'm trying to put in place a script that will start an agent using the SDK with the Azure DevOps MCP server. For authentication, I need to use the environment variable as specified in the documentation ADO_MCP_AUTH_TOKEN however it seems that passing the environment variables in the MCP server configuration doesn't work at all ...

Code

import { CopilotClient } from '@github/copilot-sdk'
import process from 'node:process'

async function main() {
    const client = new CopilotClient({
        autoStart: true,
        autoRestart: false,
        logLevel: 'all',
        githubToken: process.env.GITHUB_TOKEN,
        useStdio: true,
    })

    const env = {
        ADO_MCP_AUTH_TOKEN: process.env.SYSTEM_ACCESSTOKEN
    }

    const session = await client.createSession({
        model: 'gpt-4.1',
        mcpServers: {
            devops: {
                type: 'stdio',
                command: 'npx',
                args: [
                    '-y',
                    '@azure-devops/mcp', process.env.ADO_ORG,
                    '-d', 'core', 'work', 'work-items',
                    '--authentication', 'envvar'
                ],
                env,
                tools: ['*']
            }
        }
    })

    session.on(event => console.dir(event, { depth: 6 }))

    const response = await session.sendAndWait({
        prompt: `In the project "${process.env.ADO_PROJECT}", what does the work item with ID "30026" look like?`
    })
    if (!response) {
        throw new Error('No response received from Copilot')
    }

    console.log('==== Response from Copilot ====')
    console.dir(response, { depth: 6 })
    console.log('==== Response from Copilot ====')

    await session.destroy()
    await client.stop()
}

main()

[github-actions]

Thank you for reporting this issue, @matteo-ladrat-Legrand!

I've labeled this as bug and sdk/nodejs since it involves the Node.js SDK and MCP server environment variable handling.

This appears to be related to issue #163, which reports similar problems with environment variables not being passed to MCP servers (in that case for Python SDK). The issue seems to affect multiple SDK implementations.

Your reproduction code is very helpful. A maintainer will investigate the root cause of why the env property in the MCP server configuration isn't working as expected.

AI generated by Issue Triage Agent

[matteo-ladrat-Legrand]

I found a workaround to load environment variables :

const env = {
    ADO_MCP_AUTH_TOKEN: '${SYSTEM_ACCESSTOKEN}'
}

However, I think the initial code should be working based on documentation ....

[SteveSandersonMS]

Thanks for reporting it, @matteo-ladrat-Legrand.

We have a fix in flight at the moment - hopefully it will be merged and released in the next day or so. Just waiting for a runtime update to go through.

[matteo-ladrat-Legrand]

Thanks @SteveSandersonMS
Looking at the PR, does that mean that we are now forced to send actual values instead of the name of an environment variable ?

I'm asking that to know if I will have to change my code 😂 Indeed, I realized this and modified my code to pass the name of the environment variable (#444 (comment)) before your answer

[SteveSandersonMS]

Looking at the PR, does that mean that we are now forced to send actual values instead of the name of an environment variable ?

Yes, exactly. Sending the name of an environment variable was an unintentional design for the SDK and didn't make sense. So yes you will need to change to the more straightforward alternative of just sending the value you want.