Generative engine optimization for ecommerce

The short answer

How an AI assistant reads a store

When a shopper asks ChatGPT, Gemini or Copilot for a product, the answer is built from three sources:

• Search indexes. The assistant searches the web (Google's index, Bing's, or its own crawler such as OpenAI's OAI-SearchBot) and reads the pages it finds.
• Product catalogs. Structured data sent by your platform: Shopify Catalog feeds ChatGPT, Copilot and Google's AI surfaces, and Merchant Center feeds Google's Shopping Graph.
• Agents. Software that opens your site and clicks through it. Google notes that browser agents read screenshots, the page structure and the accessibility tree, and Microsoft's Playwright MCP works from the accessibility tree instead of pixels.

The accessibility tree is the same structure screen readers use. If a button has no name for a screen reader, it has no name for an agent either.

What Google, OpenAI and Microsoft actually say

• Google Search Central

  There are no additional requirements to appear in AI Overviews or AI Mode, nor other special optimizations necessary.

  No special schema and no need to split content into small chunks. Merchant Center and Business Profile help products show up in AI answers.

  Read Google's guidance

• Google-Extended

  Google-Extended does not impact a site's inclusion in Google Search nor is it used as a ranking signal in Google Search.

  It controls whether Gemini can use your content for training and grounding. To stay out of AI Overviews you would use nosnippet or noindex, not this.

  Google's crawler docs

• OpenAI

  OAI-SearchBot is used to surface websites in search results in ChatGPT's search features.

  GPTBot is the training crawler, and blocking it does not remove you from ChatGPT search. Product results are not ads: merchants rank on availability, price, quality and whether they are the maker or main seller.

  OpenAI's crawler docs

• Microsoft

  Traditional SEO fundamentals still matter.

  It also warns against hiding key answers in tabs or expandable menus. Bing Webmaster Tools has an AI Performance report, in preview, that counts your citations in Copilot.

  Microsoft's guidance

The platforms don't agree on every detail (Microsoft favors content in smaller pieces, Google says it isn't needed), but they agree on the base: crawlable, indexable, clear pages.

The checklist in code

Tick what your store already does.

Product data that answers questions

Shoppers ask assistants full questions, like "waterproof hiking boots under $150 that run wide". The assistant can only match what your data says. Shopify sends AI channels each product's "title, description, options, images, price, availability, and other key attributes", and Google's Merchant Center advice for AI Mode is the same: put real search terms in titles and descriptions and fill in missing attributes.

On Shopify, Catalog Mapping can take the title, description and category from metafields, so data you already keep can feed AI channels.

llms.txt: what it is and what it isn't

llms.txt is a Markdown file at your site's root that summarizes the site for language models: an H1 with the name, a short summary and lists of links to key pages (llmstxt.org).

1# CodeBulls

2> Web development and eCommerce agency. CRO, Shopify, WordPress, custom WordPress plugins and white-label development for agencies.

3## Services

- [CRO (Conversion Rate Optimization)](https://codebullsteam.com/cro): heuristic audits, A/B testing... One-off CRO audit from USD $1,500.
- [Shopify Development](https://codebullsteam.com/shopify): custom themes, private apps, migrations and integrations.

• What it isn't: a ranking factor. Google says maintaining one "will neither harm nor help your site's visibility or rankings in Google Search", and in 2025 Google's John Mueller wrote that "no AI system currently uses llms.txt."
• Why we still add one: it takes an hour, it gives agents a clean map of your offer, and Chrome's Lighthouse checks it in its experimental Agentic Browsing category. That check needs at least one link in Markdown format; ours failed until we fixed the format.
• On Shopify you can serve it from a page template or an app; on WordPress, as a static file.

Shopify Agentic Storefronts and buying inside AI

Agentic Storefronts makes Shopify products discoverable in ChatGPT, Google AI Mode and Gemini, Microsoft Copilot and Meta's AI, using Shopify Catalog. It's "active by default for eligible stores", with no plan restriction, and so is direct checkout on the channels that offer it.

All channels also need your terms, privacy and refund policies filled in. You manage each channel, and turn direct checkout on or off, in Sales channels > Agentic in your Shopify admin.

• ChatGPT is discovery only: shoppers find the product in ChatGPT and finish on your checkout, and orders arrive in your admin with ChatGPT referral attribution.
• Direct checkout is on by default, with limits: Google Analytics and custom pixels don't fire there (only server-to-server events do), and subscriptions, bundles, customizable products, local delivery and in-store pickup aren't supported.
• WooCommerce: agentic checkout and the new commerce protocols are announced as "coming soon". Today, syncing your catalog to Merchant Center with Google for WooCommerce is the main path into Google's AI shopping.

How to measure AI traffic

Since May 2026, GA4 has a default AI Assistant channel for visits from sources like ChatGPT, Gemini and Copilot. Not everything lands there:

Purchases made inside an AI's direct checkout skip your pixels, so they only show up in Shopify, under the sales channel and referral of each order.

In Bing Webmaster Tools, the AI Performance report shows how often Copilot cites your pages.

What not to pay for

Most of what's sold as "AI optimization" is either standard SEO with a new name or something no one can promise.

About the author

Juan Camilo Alzate · Product Design Lead at CodeBulls

Designs the stores and interfaces our team builds, with a focus on accessibility.