"If you have some of the information about a Topic but are unsure about its tags, you can search with other parameters in the field search. "

This tends to imply that searching with fields is somehow secondary to searching with tags. I would say something like:

"The search fields can be used to search for topics based on the textual content of a topic's property such as title, xml, description, ID and more. Search fields can also be used to search for the presense or absence of associated bugzilla bugs, and find topics that are referenced by specified Content Specifications".