How to get the instance of active EditorTool?

Hi, I'm trying to add my custom EditorTool to SceneView. I want to change some properties like a brush color and a brush size of my custom tool, so writing a code to show a Overlay in SceneView. It shows ColorField on Overlay. But I encountered the issue that ToolManager doesn't have the method to get instance of current active EditorTool. So I can't set the Color value of ColorField to my custom EditorTool.

How to get the instance of active EditorTool? Or should I set Color value to a static member of my custom tool?

Thanks!