If you’re telling new hires that your dress policy is “business casual,” you can bet they’ll do three things before they show up for work the next day.
They are:
Google “business casual”
Then, after reading too much confusing and contradictory advice online, they’ll call a friend to ask “Hey Mike, what the heck is business casual?”, and
Overdress for their first day of work (and for a few days thereafter until they pick up on what your version of business casual really is).