Write the specifics a gifter can't guess from the link: size, colour, the exact variant, and a quick word on why. A clear description means people pick the right thing first time.
What to include
Size, colour, and variant. Wishpicks has no separate field for these, so they go here. "Size M, the navy version, two please" is plenty.
Which exact item you mean, if the product page shows several options.
A reason, when it helps. "This replaces my old one" or "the blue matches my kitchen" makes it easy for someone to choose confidently.
A backup that would also work, so gifters have somewhere to go if your first choice sells out.
What to leave out
Your home address, above all. There's no address field on Wishpicks, and your description and notes are visible to anyone who can see the list, so never type a home address on a public wishlist. Use a neutral line like "message me for delivery details" and arrange it privately. The Delivery and Addresses collection covers how.
The same goes for anything else you wouldn't want every viewer to read. Gifters and guests see both the description and the notes.
Good to know
Keep it short. A couple of clear lines beats a long paragraph, and you can update it any time; see "How do I edit a wish?" It's worth setting a priority too, so gifters know which wishes matter most. See "How do I add notes, priority, or details to a wish?"