Before I wrote this, I talked to a lot of music supervisors, and they stated they would prefer that people who submit music music for their projects, briefs and general pitching include both artwork and lyrics in their metadata. Here’s their thinking:
Artwork: Your artwork helps to provide a way to promote yourself, your name and your sense of your song and your brand. It helps you to be more memorable. And it’s another area you showcase your creativity.
At the very least, you should include a picture of yourself and the name of the song. That way they can more easily connect you to your music.
Lyrics: Lyrics are vitally important to many scenes, ads and projects, and from the get go, music supervisors want as many details as possible for a song, and they need to know the lyrical content of a song clearly and quickly. Waiting for your lyrics could make them move on to the next song, especially with a tight deadline.
So at the end of the day, I believe the best practice is for you to include both artwork and lyrics in your metadata (and make sure you include translations if it is in a language other than English).