But no, good description doesn't mean long and drawn-out and flowery or purple. It's about word choices and structures to conjure the right images in the readers' mind. The trick is not to describe exactly what it is like you're actually taking a photograph, but to connect with your readers' experiences -- for example, everyone has seen sunsets, but if you use the right words, you can really bring a specific image to your readers by way of their own experiences and imagination. That's what description is about.
For example, in this passage, there really isn't a lot of descriptive words or long sentences but hopefully it does conjure the right images in the readers' mind:
They wound through a labyrinth of narrow alleys, deeper into this underclass fortress, the walls of people beginning to suffocate her. The air was hot and spicy with the smell of roasted cuttlefish, steamed fish balls, fried tofu, and curry with coconut milk. Grace elbowed her way through the passages lined with vendors. A fortuneteller sat in her corner shop, the bright red sign on the cracked window a hypnotic twirl of questions: What will happen to all of us? How many people are going to die?
Also, if you weave your description with the action and plot movement, it's more vivid and relevant. It's not a good idea to stop your plot and start talking about the moon and stars.
To me, descriptions are also cumulative. You don't need to stop the action and spend five paragraphs describing your world. Instead, just bits and pieces, here and there, and eventually they all add up to form a complete picture. That's a more effective and powerful way to do descriptions.