Warn the people, Tell the papers, I'm much too tired for Christmas capers."" So said Santa. But he changed his mind when the children of all nations turned the tables and sent Santa presents, like guppies and jam and lemon drops. The McGinley magic and Kurt Werth's brightly colored and amiable illustrations of gnomes and reindeer tell the impish story of why . . . ""You can count your blessings, on fingers and thumbs, for yearly, newly, faithfully, truly, somehow Santa Claus always comes."" Firmly sewn.