I want headlines to provide me with a concise summary of what I can expect to find within an article, so I can decide whether it's worth my time. But headlines

I want headlines to provide me with a concise summary of what I can expect to find within an article, so I can decide whether it's worth my time. But headlines don't always do this very well; sometimes they promise more than the article delivers, and sometimes they're just poorly written and miss the point. The tl;dr convention exists, and thrives even on HN, because we recognize the value of our own and others' time and attention. As you say, it's a valuable way to find out if the story is actually interesting or worthwhile.