Oyatoi' refers to the hiring of someone (unnecessary to be a foreigner) who does not belong to a samurai family for his or her special skills or knowledge in order to accomplish the bakufu's 'goyo' (official business).
「御雇（おやとい）」とは（とくに外国人に限らず）武家でない身分の者を、その専門技芸において幕府の「御用」に徴用することを指した。