What are the descriptions of the short chapters?
short chapters refers to ParagraphNum < 150
SELECT DISTINCT T2.Description FROM paragraphs AS T1 INNER JOIN chapters AS T2 ON T1.chapter_id = T2.id WHERE T1.ParagraphNum < 150
database name:db_id shakespeare
chapters table chapters Cols: id dtype integer, Act dtype integer, Scene dtype integer, Description dtype text, work id dtype integer, 
characters table characters Cols: id dtype integer, char name dtype text, abbreviation dtype text, Description dtype text, 
paragraphs table paragraphs Cols: id dtype integer, paragraph number dtype integer, Plain Text dtype text, character id dtype integer, chapter id dtype integer, 
works table works Cols: id dtype integer, Title dtype text, Long Title dtype text, character id dtype integer, genre type dtype text, 
