Many home sellers and/or Realtors think it's a good idea to be at the home when a potential buyer and their agent is touring the home.
It's almost always a HORRIBLE idea:
(1) Buyers Cannot Be Sold. Trying to point out the things you like about the house is just guessing - the buyer and their agent know what's important to them - you don't. Instead, leave a flyer with all the various features, improvements, and upgrades. If there are questions, their agent will get back to yours.
(2) Outside Presence Stifles Freedom. No buyer or their agent is going to freely speak with you or your agent in the home. They also might avoid looking at certain areas.
(3) It Shortens the Tour. Having some else there makes the buyers' visit, at some level, feel like an imposition. And no one likes that. Your for-sale house is a product - your presence can remind them that it's someone else's home. That's awkward and they'll be more likely to leave sooner rather than later. And that's exactly what you do NOT want to happen. You want them to have PLENTY OF TIME to have the opportunity to imagine that the house could be their new home.
One potential objection: What about our stuff? Our privacy and security? Firstly, if part of the agenda of having someone there is to keep an eye on the visitors, they'll sense that. And hate it. Secondly, if you've got valuables or treasured items, get them out of the house!