Before writing the 280-character message, explain your project aloud in one breath. Tell someone what it is, who might use it and what they will find after clicking. If you need a long preface or a list of features before reaching the point, the page needs a narrower focus.
Suppose you have built a tool for sharing rarely used household equipment. “Profiles, requests and an easy dashboard” names the parts. “Borrow a ladder from a neighbour instead of buying one” names the useful outcome. The short message can add the condition that matters most, such as the neighbourhoods served or whether the tool is open to use.
Write down the sentence that sounded natural when spoken. Trim it until it fits without removing the essential detail. Then compare it with your destination page: does the visitor find the same thing you promised? Clear language is especially important when the page is one of many cards in an edition.