It is still not known if Steamtools is safe. It is possible to download games like Steamtools via GreenLuma but it takes a bit more work.

First of all, download GreenLuma. I use a GreenLuma gui which also allows you to manage your AppList. (https://cs.rin.ru/forum/viewtopic.php?f=14&t=151251)

Steamtools works via unlocking app/depot ids and adding decrypt keys (via a lua file) and manifests. This allows you to download your game directly from Steam servers. GreenLuma is solely for unlocking stuff (via the AppList folder), but the decrypt keys can be used to download games.

Piracybound provides these files (https://www.piracybound.com/manilua). For these files to work with GreenLuma, you need to manually copy manifests, add the decryption key and add the game and its depots to AppList.

GreenLua (https://www.piracybound.com/discord, find in announcements) allows you to drag and drop lua and manifest files and sets this all up for you, if you dont trust it you can do it manually.
IMPORTANT the game won't show in your library of you do it manually, press the install button for your game on steamdb or run steam://install/APPID.(https://www.youtube.com/watch?v=YVdFtd94pgk)

Now just restart Steam and the game should be in your library and be downloadable.

Some games might not work (Replicube didnt for me), you will have to use GreenLuma as it is intended too, (provide your own clean steam files) which you can get from cs.rin.ru or https://github.com/SteamAutoCracks/DepotDownloaderMod. Find a other guide for this. (Also using the gui remove all depot ids of your game, keep the game id itself and clean the cache)

If you need help feel free to dm me.