A summary should leave a trail back to the details it compressed.

A summary is only trustworthy if someone can get back to what it compressed. Without that trail, the reader has to accept the compression on faith, and any distortion introduced along the way becomes permanent, since there is no route back to check it.

When you summarise, leave the references, the source, the underlying numbers, the link to the full version. It takes a minute. And when you receive a summary of something important, ask for the detail behind one specific claim, since the answer tells you a lot about how the rest was made.