Building on https://phabricator.vyos.net/T958, it appears that setting a Wireguard description with a space results in an error:
brooks@border# set interfaces wireguard wg0 description "Tunnel" [edit] brooks@border# set interfaces wireguard wg0 description "Tunnel tunnel tunnel" interface description is too long (limit 100 characters) Value validation failed Set failed [edit]
Despite the description being under 100 characters.