User mentions in REST API POST comments

There is no mention on the documentation on whether this is even possible but other platforms such as Slack allow you to mention other users using their API. For example in Slack you write a message like this: Hello, <@U12345678>! and the user is mentioned. I tried different potential formats but to no avail. Is there any way to mention a user in a comment created using the API or can it be added in the future?