Does A Novel Belong In the Forgotten Realms?

To put on the list, or to not put on the list: that is the question.

Since diving into reading the Forgotten Realms I have run into a few items that have confused me somewhat. So far there have been two types of cases.

First is exemplified by Murder in Tarsis by John Maddox Roberts, Fistandantilus Reborn by Douglas Niles, as well as Under the Crimson Sun by Keith R. A. DeCandido; books in the Mysteries, The Lost Gods, and Abyssal Plagues series respectively. At first glance one might notice that neither of these take place in the Fearûn or the Forgotten Realms at all. Murder in Tarsis and Fistandantilus Reborn are part of the much praised Dragonlance, and Under the Crimson Sun is set in the bleak Dark Sun setting. I have not read either of these but the fact that neither of these novels are in the Forgotten Realms but are listed in series that are leaves me wondering if I should read them on my quest.

The Second is something I have only identified once. Vampire of the Mists by Christie Golden is a novel of the Ravenloft setting. I have yet to read it but as far as I am aware the novel partially takes place in Waterdeep on the Sword Coast in the Forgotten Realms. Should this be on list to read or should it not?

If anyone has any thoughts I would love to hear them. Though I think I will get to the three mentioned here, it may be a long while because of their odd predicaments.