git silently ignores aliases of existing commands

Everyone says "git tag" does the wrong thing by default and what you really want is an annotated tag with "git tag -a". So I figured I'd fix the default and in my .gitconfig added:

[alias]
    tag = tag -a

and considered it done. Weeks later I discovered git was ignoring that alias and I was still making lightweight tags.

It would be nice if git used the alias *before* the installed command. This lets me fix/change default behaviors without having to come up with a new command. (Another handy example: blame = blame -w) It doesn't do anything useful right now anyway.

Whether or not that changes, if an alias is being ignored git should warn me.
 This informs the user their perfectly sensible action has not done what they
expected.  In addition, should git add a command in the future which conflicts
with the name of an alias they'll know.

PS I couldn't find anything obvious about where to send bug reports / feature requests in the git man page, just "general upbringing" pointing here. It would be helpful if it was a bit more clear. None of "bug", "report" or "issue" pointed at anything relevant.