Specify one or more words to use in a search query for finding items on eBay. By default, queries search item titles only. When running queries, it is best to include complete keywords values--eBay checks words in context with each other. If you are using a URL request and your keyword query consists of multiple words, use "%20" to separate the words. For example, use "Harry%20Potter" to search for items containing those words in any order. Queries aren't case-sensitive, so it doesn't matter whether you use uppercase or lowercase letters.
The words "and" and "or" are treated like any other word (and not their logical connotation). Only use "and", "or", or "the" if you are searching for listings containing those specific words.
findCompletedItems requires that you specify either keywords or a categoryId in the search criteria.