Having your clients send an application specific MIME type can actually be better for browsers as well. All you need to do is provide a representation of your resource in HTML which browsers will request by using "text/html" in the Accept header.
I've found this a nice addition to documentation and, depending on how well the HTML representation has been done, is great for learning/exploring an API.
Here's a (fairly old) blog post describing how escrow works in OpenBazaar:
https://blog.openbazaar.org/how-moderators-and-dispute-resol...