Linking to descriptions policy
You're allowed to include one link in your listing that will take the buyer to a page that further describes the item being sold. The primary intent of the link must be to further describe the item and the link must conform to our links policy.
Any relevant information about the item needs be shown as text within the item description. Placing information within a photo or image is against eBay policy and may confuse potential buyers.
Make sure your listing follows these guidelines. If it doesn't, it may be removed, and you may be subject to a range of other actions, including restrictions of your buying and selling privileges and suspension of your account.
If you include a link to a web page that further describes the item, that page may contain links to other pages that offer items for sale outside of eBay.
Why does eBay have this policy?
This policy allows sellers to provide more information about the item for sale. This additional description can be posted outside of eBay, allowing the buyer to learn more about the item, but it can't allow or encourage the buyer to purchase the item outside of eBay. Purchases completed outside of eBay may be unsafe and are against eBay policy.