What does cryptsetup luksAddKey --new-key-description do?

I can't seem to figure this out through the usual means. `man cryptsetup-luksAddKey` says:

--new-key-description text : Set the key description in the keyring that will be used for new passphrase retrieval.

... which I assume is the kernel's keyring. Passing --new-key-description="Value" yields:
# Verifying key from keyslot 0, digest 0.
# Requesting key Value (user type)
# keyring_request_key_id failed with errno 126.
Failed to read passphrase from keyring.
# Rolling back in-memory LUKS2 json metadata.
# Releasing crypt device /home/me/dev.img context.
# Releasing device-mapper backend.
# Closing read only fd for /home/me/dev.img.
Command failed with code -1 (wrong or missing parameters).

luksAddKey works fine without --new-key-description. I'm trying to understand what this parameter does and how it should work. I'd also like to ask that the manpage be updated to explain this parameter a little more thoroughly. I'm not sure how I am supposed to know what I'm doing wrong with the documentation. AI said it should work, so there must be a problem with my bash or cryptsetup installation. Something's obviously missing.