Python has many parameter types: positional-only, positional-or-keyword, keyword only, etc. Even if we don't add "/", it would be nice to have hints when we put the mouse cursor on a function parameter.

Something like:

function: demo(arg1, *, arg2, arg3=None)

arg1 hint: *arg1* is the first mandatory parameter (kind: positional-or-keyword)
arg2 hint: *arg2* is the second mandatory parameter (kind: keyword-only)
arg3 hint: *arg3* is an optional parameter (default: ``None``, kind: keyword-only)

Maybe we can also add hints on '*':

* hint: Marker for keyword-only parameter

... I have no idea how complex it would be to implement such Sphinx extenstion, or maybe even implement it in Sphinx.