[BUG] env variable expansion not working in plugin .mcp.json

[yonijacobi]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

When including env variables in .mcp.json file inside plugin root folder instead of reading the value of the variables it reads the var string as is ("${VAR}"), with same file in the project root instead of the plugin folder it not happens

What Should Happen?

It should use the envioronment variables like in regular .mcp.json file, as mentioned in the docs

Error Messages/Logs

Steps to Reproduce

1. install plugin with mcp servers using the builtin /plugin comand
2. restart claude and run /mcp to verify the mcp servers from the plugin installed
3. use tool that requires permissions or other usage of env variables

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

2.0.14

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] MCP headers with environment variable substitution not being sent from .mcp.json #6204
2. [BUG] variable expansion not working in .mcp.json #3239
3. [BUG] Environment variables from env section not passed to MCP servers #1254

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
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🤖 Generated with Claude Code

[yonijacobi]

👎

[creatorrr]

I had the same experience. Env var substitution works for the ones defined in local .mcp.json but not when inside a plugin's .mcp.json file

[evrimalacan]

I got very excited about the plugins and quickly created a marketplace with our company's favorite MCPs hoping this will give us an easy way to share MCPs, only to notice the same problem... Each server in the plugin's .mcp.json is throwing authentication errors 😭

By the way, this issue seems to affect hooks as well: #9447

[joelclimbsthings]

Having the same issue 🤚🏻

[vmandela]

Have the same issue. ${PWD} is passed literally to the mcp invocation without environment variable expansion.

{
  "mcpServers": {
    "serena": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/oraios/serena@v0.1.4",
        "serena",
        "start-mcp-server",
        "--context",
        "ide-assistant",
        "--log-level",
        "DEBUG",
        "--project",
        "${PWD}"
      ]
    }
  }
}

[hongwei0417]

Same issues from notion mcp env variable

"notionApi": {
	"command": "npx",
	"args": ["-y", "@notionhq/notion-mcp-server"],
	"env": {
		"NOTION_TOKEN": "${NOTION_TOKEN}"
	}
}

[theagenticguy]

Also have the same issue:

{
  "mcpServers": {
    "context7": {
      "type": "http",
      "url": "https://mcp.context7.com/mcp",
      "headers": {
        "CONTEXT7_API_KEY": "${CONTEXT7_API_KEY}"
      }
    },
    "deepwiki": {
      "type": "http",
      "url": "https://mcp.deepwiki.com/mcp"
    },
    "brave-search": {
      "command": "npx",
      "args": ["-y", "@brave/brave-search-mcp-server"],
      "env": {
        "BRAVE_API_KEY": "${BRAVE_API_KEY}"
      }
    },
    "tavily": {
      "type": "http",
      "url": "https://mcp.tavily.com/mcp/?tavilyApiKey=${TAVILY_API_KEY}"
    },
    "exa": {
      "type": "http",
      "url": "https://mcp.exa.ai/mcp/?exaApiKey=${EXA_API_KEY}"
    }
  }
}

2.0.24 (Claude Code)

[Manouchehri]

Likewise, glad to know it's not something I was doing wrong on my end.

[dvic]

I can confirm this bug as well.