I'd appreciate an application directly in the app. In doubt, I simply deny such requests.
Don't ask the user to approve something he: doesn't know what you want to do with it and the thing screams "don't do it" at the particular situation
Authy asks me for my mobile phone number – once to 'securely identify' me and once to create an account, apparently with Authy.
Why is an account necessary for such an app? Can't I use Authy without an account?