When lugging all your camping gear up a hill, the lighter it is, the better. However, too light and it may not afford the protection you need against the mountain elements.
In this guide, the ultralight 3-season tents range from around 500g to 1kg. These tents are generally constructed from cutting edge materials and are more expensive. They're also generally unsuited to winter use.
Between 1kg and 1.5kg is fairly normal for a standard one-person tent and won't weigh you down too much on the trail. A decent one-person winter tent will weigh more towards 2kg and will give you all the protection you need against gnarly conditions.
Above 2kg and you'll start to feel it on those long ascents. It might be worth spending more on something lighter.