I didn't see specific mention of how this is obtained by the wish service.

It would be interesting to get a full UX scenario of a user with a specific need using the technology.

It is not clear currently if a Web site can host both the link/rel uri and the tool href on different domains.

{
  name:   "Wunderbar Image Editor"
, action: "edit"
, types:  ["image/*"]
, href:   "editor-implementation.html"
}

I'm a Web site www.example.org owner, I have assets and my tool of choice for dealing with them is cooltool.example.com. The JSON description file is on another domain name which is nginx.example.org.

Would it be possible to allow HTTP Link: for the system. link/relis dependent of HTML and there might be opportunity to make the mechanism usable by other formats.