Google and other search engines always want to offer the most relevant content for a specific search result. The relevance of content depends on many factors. Different studies show that the number of words is an important factor. Read this article about the ideal content length for SEO.
In Textmetrics we determine the number of words based on an algorithm, in which we take the given keyword in account. Also, in Textmetrics you have the possibility to work with an SEO rule set which is less strict in terms of the number of words on a page. The rule set option allows you to choose between a blog/article and product page rule set. Read more about this rule set (also called: text type).