"Start of document" as search option

It would be nice if a search engine offered the option of having the first few hundred characters of text in a document be the text displayed in the search results, in lieu of the passage(s) containing the search terms, which seems to be the standard practice with all the major search engines. The rationale is that sometimes I'm searching specifically for a document to link to, for the purpose of explication of something in my own writing. I wish to avoid assuming prior knowledge in my readers, but I also wish to streamline reading for those who do know the jargon. For the less fortunate group of readers, I want to provide a link to a document that explains (or at least introduces) the relevant topic in the first paragraph.