Hi,
I noticed there is a Character Tool RMB menu for Simple Male Object HDA.
Can add custom RMB menu for other HDA?

Thanks.

I don't think there a way to register a custom menu from python.
You'll need to install a user OPmenu.xml file and add your new menu in there.

Here's the reference page on menu configuration.
http://www.sidefx.com/docs/houdini15.0/basics/config_menus [sidefx.com]

If you look in OPmenu.xml file from the houdini installation, you'll notice it has a conditional menu entry for Character Tools that show up based on the asset type.
If you want your menu to show only on a specific asset type you'll have to do something similar.