Nope, we use the output log generated by MTG Arena. This output log was intentionally created to allow third-party developers to create tools and apps that interact with the game.
There is no actual confirmation about this, but based on some actions and tweets (and the fact that they continue to support the log we scrape data from) we can say they have no issues with us. However, there is no guarantee they will not terminate it if they feel like doing so.
First and foremost you need to start MTG Arena. Once you have logged in MTG Arena, you can start MTG Arena Tool, sign up (create a new account) and you are ready to go!
NO, do not ever input your MTG Arena credentials anywhere except MTG Arena itself. Our login services are exclusive to MTG Arena Tool and are not related to the game.
MTG Arena Tool reads trough your entire log file at startup, that means it can read past games even when you did not have it running then. The log file is cleared by MTGA every time you initiate it, so with MTG Arena Tool you will probably see past games but only a few.
They come from the Magic Community Set Reviews.
Currently progress is stored locally, that means you can only see the history of games you played in the PC you played them in. Sync features are in the works!
Check this out: youtube.com/watch?v=bjmX7NdJX8w. You just have to change compatibility mode and you're good to go. Remember to set 'Persistent mode' on settings too!