REST endpoint support for HTML tags in input string

should a REST web service endpoint support , HTML tags in the input string ? or should it strip it out? I have an endpoint that takes in a string input and persist it. The front end form currently allows users to put in HTML tags in this field , if needed. eg: hi is considered valid. if this is passed onto the Web service endpoint, how should we handle this as per the BEST practises?

thanks in advance!