Q:

How to pull ID3 tags from online database(s) for specific albums?

My late wife had a HUGE collection of Vinyl and more than a few CDs.  I had some of each myself.
Now I'm retired and traveling, so I'm putting them all in iTunes.  The CDs mostly imported with all the proper tags.   Vinyl copied from a USB turntable to MP3 files did not, because iTunes only checks Gracenotes when importing CDs.  Audio CDs made from the ripped files occasionally matched but usually didn't.
Tidy up iTunes library? and items linked from it gave me several suggestions for tools to try.  None of them worked.  They couldn't even match files imported from legal commercial CDs that iTunes had already correctly matched.  This is, I imagine, since most "fingerprinting" algorithms depend more on the way the tracks are assembled than the actual music in each file.  (Yet I remember, some time ago, advertisements for apps/services that allegedly allowed a smart phone to identify a song from the audio picked up by the microphone.)
In almost all of my cases, however, I already know which album it is, so what I would really like is a tool that will let me tell it a group of files and some sort of ID or URI of the album in Discogs/CDDB/Gracenotes/MusicBrainz/etc. and have it add or correct all the tags (so I don't have to type them all in one at a time.
Bonus if it can also download cover art.  And run on MacOS.

A:

the beets cli utility can query musicBrainz to get the id3 tags for your library.  Install beets from homebrew and run beets. Give beets a hint as to what you think the album is.
brew install beets
cd ~/elton/GBYBR
beets import Goodbye Yellowbrick

Choose [A]ccept [M]ore or A[B]ort when beets tells you what it's about to tag your files as.
source: https://media.readthedocs.org/pdf/beets/latest/beets.pdf
details: https://beets.readthedocs.io/en/latest/guides/tagger.html
If you would rather write the tags yourself I like 
id3tag 

link: Is there a good command-line ID3 tool for OS X?

