Noteworthy histories . . . briefly considered; Yankees at the Court, by Susan Mary Alsop. New York: Doubleday & Co. 319 pp. $17 .95.

This highly readable account of America's first diplomats abroad during the years 1775-85 will enlighten both serious students and those scantily acquainted with this period. Alsop, a descendant of John Jay, passes along new information gleaned from private papers. She does it with a breezy style that transforms stale historical facts into a freshly told tale.

She deals primarily with America's first ambassadors to Versailles - Franklin , Jay, and Adams, who were troubled by loneliness and a shortage of money from an impecunious Congress. In fact, Jay was once reduced to asking the Spanish to pay a bill for $333 when his funds ran out.

Alsop also deals with daily court life and life in Paris, where fashionable ladies wearing skirts 21 feet around and hairdos a foot and a half high would descend directly from their carriage to the doorstep to keep street mud from destroying their satin slippers; and where pedestrian casualties were so common that a standard stipend was set for the loss of a limb or a life.