From what I've seen of them, ants of any kind in pots are bad. That looks like the kind commonly called "piss ants" around here. Their tunneling/nesting destroys the soil structure/drainage in pots, as well as bringing pests to plants, as mentioned above, including the insidious and impossible to see root mealybugs. I have been battling ants for years in potted plants (which I have over 100 of, some years,) and they are my primary nemesis to having plants do well. They seem to prefer some pots over others, but I can't find the key to what the difference is.
If you can follow their trail to their ground nest, pouring boiling water on that will kill a LOT of them.
