as per the documentation over here
I am able to post on behalf of the user of my application and as well tag user's friends by using app access token.
but I have problem with mention. As said in documentation my message formate is
in facebook it look's same
Testing @[MyFriendsFacebookId] , it is supposed to be
Testing [Name of my friend with the link to his ACCOUNT]
- at first, the YourFriendFacebookId is got from /me/taggable_friends api, not from /me/friends api。I have made this error before. and the /me/taggable_friends api need additional permission for non-developer and non test users, you must require it from facebook. the api link is here: https://developers.facebook.com/docs/graph-api/reference/user/taggable_friends
- if you mention friend in a custom action, you still need require "tag" permission for you custom action when define it. (but I don't know whether need and how to require "tag" permission for common action). If it is not work, I think you may still need to require "User Messages" permission.
you can't mention friends in posts via app as far as I know. There's a discussion here on SO on the same topic. I'll search it for you.