[{"_id":1,"tags":["school","home"]},{"_id":7,"tags":["home","test"]},{"_id":2,"tags":["school","storage","home"]},{"_id":3,"tags":["school","storage","home","bones"]},{"_id":4,"tags":["school","storage","home","bones","milk"]},{"_id":5,"tags":["homes","maps","bones"]},{"_id":6,"tags":["xxx","yyy","zzz"]}]

db.collection.find({$and:[{tags:"school"},{tags:"home"},{tags:{$size:2}}]})