Does Codex support an equivalent of CLAUDE_PLUGIN_ROOT for an MCP server inside .mcp.json?

[tanin47]

Thank you.

[metehankaygsz]

Codex does not appear to expose a CLAUDE_PLUGIN_ROOT equivalent. Instead, plugin MCP configurations support a relative cwd, which Codex resolves against the installed plugin root.

For example:

  {
    "mcpServers": {
      "example": {
        "command": "node",
        "args": ["server/index.js"],
        "cwd": "."
      }
    }
  }

Here, cwd: "." becomes the plugin root, so paths in args can be relative to it. A subdirectory such as "cwd": "server" is also resolved beneath the plugin root.

This behavior is implemented in plugin_config.rs (https://github.com/openai/codex/blob/main/codex-rs/codex-mcp/src/plugin_config.rs). Therefore, relative cwd is the native Codex replacement for embedding ${CLAUDE_PLUGIN_ROOT} in
command arguments.

[tanin47]

Thank you sir! That works.