Describe the purchase from the shelf
Imagine the shopper facing several similar products. “Tomatoes” could mean fresh, chopped canned, or whole canned. “One can chopped tomatoes, about 400 g, for Thursday sauce” settles the important choices in one line. If any brand works, the shopper can choose based on the actual options rather than sending photos.
Say which detail matters most
Ask the shopper afterward which item was hard to identify. Improve only that entry next time. A list full of product specifications can be as hard to use as one made entirely of vague names.
Put the essential difference near the front. “Decaf whole beans; usual roast if available” gives the shopper better information than an old package photo when the shop changes its packaging. If the precise blend is essential, name it and state whether to skip the item when it is gone.
Read back the awkward items
Before the trip, ask the shopper to explain how they would recognize one unusual item. If their description points to something different, fix that entry. Do this for a first purchase or a frequently confused product, not for every loaf and onion. Save the successful wording for the next time someone else does the shop.