I did some experimenting with this as an external app tool within MusicBee today, ended up with this in the Parameters box after putting the path to my AAD/ AlbumArt.exe in the application path box:
/ar "<Artist>" /al "<Album>" /t f /mn 300 /mx 3000 /o a- /ac /p "\Art\%artist% - %album%.%extension%"
What this does when selected from the MusicBee context menu (Send To: External Tool) is open AlbumArtDownloader, search for the selected file by its Artist/Album values, and display front covers found sorted by dimensions with a minimum of 300X300 and max of 3000X3000. At this point, you can (among other things) choose to:
1. Click the "diskette" logo under the cover you want, at which point it will be auto-downloaded and saved to the path specified in the parameters (in my example it would be c:\Art), named according to "artist - album" with the extension of the original file. AAD will automatically exit after this operation.
2. Or, instead of clicking the diskette, you can right-click the chosen cover and choose "copy", and manually exit AAD. Then, right-click the music file within MusicBee and choose "Paste Artwork." This will bring up the MB option to embed the cover you chose into the file, or save/link to it. Cool!
The parameter script above was borrowed heavily from one posted in the Mp3tag forum by M3Rocket (
https://community.mp3tag.de/t/how-to-use-albumartdownloader-in-tools-for-cover-art/19422), with modifications then made to function the way I wanted it to in MusicBee.