For now We can only convert to TableTop Simulator format from deckbox.org, tappedout.net and basic text. The images are from scryfall and it just pulls the first one returned. I think that defaults to first printing.
curl https://api.mtg.fail/\?deck\=https://tappedout.net/mtg-decks/22-01-20-kess-storm
curl https://api.mtg.fail/\?deck\=https://deckbox.org/sets/2548127
curl -X POST https://api.mtg.fail -H 'Content-Type: text/plain' --data-binary @deck.txt where deck.txt contents is in this format
I curl and output right to the TTS library directory.
curl https://api.mtg.fail/\?deck\=https://tappedout.net/mtg-decks/22-01-20-kess-storm/ > ~/Library/Tabletop\ Simulator/Saves/Saved\ Objects/testing/tappedout.json