The campaign description (title, subtitle, picture, description) is the marketing message you want to deliver through this campaign.
It isn't mandatory, but if you put a description, it needs to be different from the product description, which contains only the technical information.
The idea is to deliver a marketing message related to the campaign aim.
Promote and adapt the campaign depending on the influencer targeting, seasonality (i.e. Valentines Day), special marketing operation, etc.
Don't hesitate to add pictures, moodboards, and videos to give the influencer as much direction as possible.