agents.md is a plain text file at the root of your store that tells AI agents what your store is and what its policies are, in words an agent can read without guessing.
Most Shopify stores still serve the default file, which says nothing about the store itself. You can check yours at yarvi.ai/validate.
The other thing agents rely on is the product data on your product pages. When a product page carries complete structured data, with price, stock and reviews, agents quote it accurately. When it doesn't, they guess from the page text.
Product pages in your Yarvi dashboard lists the pages agents read most, so those are the ones worth checking first. Changes to your theme are yours to make: Yarvi only reads your store.