# Is BigCommerce agent-ready? Defaults and what to fix

> BigCommerce Stencil storefronts render on the server, ship Product JSON-LD in the Cornerstone theme, and generate an XML sitemap. They lack return and shipping structured data, ProductGroup variants and llms.txt. UCP support runs through an early-access Google agentic checkout program, and Catalyst proxies /.well-known/ucp to BigCommerce.

- Source: https://is-agentic-storefront.com/guides/bigcommerce-agent-readiness
- Updated: 2026-10-15

BigCommerce's Stencil themes render product pages on the server, and the Cornerstone theme ships Product JSON-LD. Richer structured data and `llms.txt` are not included, and the [agentic commerce protocols](https://is-agentic-storefront.com/guides/agentic-commerce-protocols) layer is in early access. This guide maps each check in the [agent-ready ecommerce](https://is-agentic-storefront.com/guides/agent-ready-ecommerce) score to what a stock BigCommerce store gives you.

## What does BigCommerce give AI agents by default?

On Stencil, Handlebars templates run on the server and produce the HTML that shoppers and agents receive ([Stencil tech stack](https://developer.bigcommerce.com/docs/storefront/stencil/start/tech-stack)). Cornerstone outputs Product JSON-LD from `templates/components/products/schema.html` ([Cornerstone source](https://github.com/bigcommerce/cornerstone/blob/master/templates/components/products/schema.html)). The XML sitemap lives at `/xmlsitemap.php` ([BigCommerce sitemaps](https://support.bigcommerce.com/s/article/Sitemaps)). For agentic checkout, BigCommerce runs "Agentic Checkout with Google UCP" as an early-access program through Commerce AI Labs, configured in Channel Manager ([BigCommerce](https://www.bigcommerce.com/articles/ecommerce/google-agentic-checkout/)).

"Theme" in the tables below means the result depends on your theme. The defaults describe current Cornerstone.

### Access

| Check                                         | Default on BigCommerce                  | What to do                                                                           |
| --------------------------------------------- | --------------------------------------- | ------------------------------------------------------------------------------------ |
| [AI agents not blocked](https://is-agentic-storefront.com/checks/agent-access) | Depends on any CDN or bot rules you add | Allow [AI user agents](https://is-agentic-storefront.com/guides/ai-user-agents) in every layer in front of the store. |
| [robots.txt](https://is-agentic-storefront.com/checks/robots-txt)              | System defaults, merged with your edits | Check your edits for AI bot `Disallow` rules.                                        |
| [No CAPTCHA](https://is-agentic-storefront.com/checks/no-captcha)              | Depends on your apps and scripts        | Keep CAPTCHA off product pages and the cart.                                         |
| [No content gates](https://is-agentic-storefront.com/checks/content-gates)     | Depends on your apps                    | Don't swap the page HTML for a gate.                                                 |

### Product data

| Check                                                    | Default on BigCommerce                                                      | What to do                                             |
| -------------------------------------------------------- | --------------------------------------------------------------------------- | ------------------------------------------------------ |
| [Product facts in HTML](https://is-agentic-storefront.com/checks/ssr-product-facts)       | Rendered on the server by Stencil                                           | None for Stencil                                       |
| [Product JSON-LD](https://is-agentic-storefront.com/checks/product-json-ld)               | Cornerstone: `Product` with SKU, MPN, GTIN, brand, `Offer` and availability | Update older themes. Fill in GTIN and brand.           |
| [Variants modeled](https://is-agentic-storefront.com/checks/product-variants)             | Single `Product`, no `ProductGroup`                                         | Extend `schema.html`.                                  |
| [Return and shipping data](https://is-agentic-storefront.com/checks/return-shipping-data) | Not in Cornerstone                                                          | Add `MerchantReturnPolicy` and `OfferShippingDetails`. |
| [OpenGraph price tags](https://is-agentic-storefront.com/checks/opengraph-product)        | Theme                                                                       | Check your theme's head for `og:` price tags.          |

### Discovery

| Check                                                  | Default on BigCommerce                                   | What to do                                          |
| ------------------------------------------------------ | -------------------------------------------------------- | --------------------------------------------------- |
| [Sitemap](https://is-agentic-storefront.com/checks/sitemap)                             | `/xmlsitemap.php` on Stencil, `/sitemap.xml` on Catalyst | Make sure robots.txt lists it.                      |
| [Canonical and status codes](https://is-agentic-storefront.com/checks/canonical-status) | Theme                                                    | Keep a self-referencing canonical on product pages. |
| [Performance](https://is-agentic-storefront.com/checks/performance)                     | Theme and scripts                                        | Trim third-party scripts.                           |
| [Markdown alternative](https://is-agentic-storefront.com/checks/markdown-alternative)   | Not documented                                           | Low weight. You can skip it.                        |
| [llms.txt / agents.md](https://is-agentic-storefront.com/checks/llms-txt)               | Not documented                                           | Add one if you can serve a root file (see below).   |

### Operability

| Check                                            | Default on BigCommerce                                                                         | What to do                                                    |
| ------------------------------------------------ | ---------------------------------------------------------------------------------------------- | ------------------------------------------------------------- |
| [Add-to-cart in a form](https://is-agentic-storefront.com/checks/add-to-cart)     | Cornerstone: `<form method="post" action="{{product.cart_url}}">` with `<input type="submit">` | Keep the form if you customize the product view.              |
| [Variant controls](https://is-agentic-storefront.com/checks/variant-controls)     | Cornerstone: radio inputs with labels, including swatches, plus `<select>`                     | None for Cornerstone                                          |
| [Accessible names](https://is-agentic-storefront.com/checks/accessible-names)     | Theme                                                                                          | Give icon-only buttons a name.                                |
| [Site search](https://is-agentic-storefront.com/checks/site-search)               | `/search.php?search_query=term`                                                                | None                                                          |
| [Policy links](https://is-agentic-storefront.com/checks/policy-links)             | You create the policy pages                                                                    | Create return and shipping pages and link them in the footer. |
| [Semantic structure](https://is-agentic-storefront.com/checks/semantic-structure) | Theme                                                                                          | One `h1`, landmarks and alt text.                             |

### Agentic commerce

| Check                                                                                                                                                                                                                                               | Default on BigCommerce                                       | What to do                                     |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------ | ---------------------------------------------- |
| [UCP profile](https://is-agentic-storefront.com/checks/ucp-profile)                                                                                                                                                                                                                  | Depends on enrollment in the Google UCP early-access program | Request early access through Commerce AI Labs. |
| [Live agent endpoint](https://is-agentic-storefront.com/checks/agent-endpoint)                                                                                                                                                                                                       | Comes with the UCP profile, if one is served                 | Skipped without a profile                      |
| [Checkout permalinks](https://is-agentic-storefront.com/checks/checkout-permalinks)                                                                                                                                                                                                  | `/cart.php?action=add&product_id=ID` exists                  | Declare a UCP permalink capability for credit. |
| [OAuth discovery](https://is-agentic-storefront.com/checks/oauth-discovery)                                                                                                                                                                                                          | Not documented for storefronts                               | Needed only with an agent endpoint             |
| Bonus checks ([WebMCP](https://is-agentic-storefront.com/checks/bonus-signals#webmcp), [A2A](https://is-agentic-storefront.com/checks/bonus-signals#a2a-agent-card), [AI Catalog](https://is-agentic-storefront.com/checks/bonus-signals#ai-catalog), [API catalog](https://is-agentic-storefront.com/checks/bonus-signals#api-catalog), [`rel="ucp"`](https://is-agentic-storefront.com/checks/bonus-signals#ucp-link)) | Not documented                                               | Optional                                       |

## How do I fix a BigCommerce store for AI agents, in priority order?

### 1. Check robots.txt and bot rules

Edit robots.txt in **Settings → Website → Search Engine Robots**. BigCommerce merges your rules with its system defaults ([BigCommerce robots.txt](https://support.bigcommerce.com/s/article/Understanding-the-Robots-txt-File)). Don't disallow AI search bots or user-initiated agents. Blocking training crawlers is your choice and isn't penalized. If you run a CDN or WAF in front of the store, allow the same bots there. The [AI user agents guide](https://is-agentic-storefront.com/guides/ai-user-agents) lists them.

### 2. Update the theme's Product JSON-LD

Cornerstone replaced its microdata with a single JSON-LD block in 2021 ([PR #2138](https://github.com/bigcommerce/cornerstone/pull/2138)). If your theme is older, or was forked before then, pull in `templates/components/products/schema.html`. Then fill in GTIN, MPN and brand on each product so those fields aren't empty.

### 3. Add return, shipping and variant data

Cornerstone's schema outputs one `Offer` and nothing about returns or shipping. Return and shipping data is the most common fail across all the stores we calibrated against. Add a `MerchantReturnPolicy` and `OfferShippingDetails`. Google accepts them at Organization level ([return policy](https://developers.google.com/search/docs/appearance/structured-data/return-policy)), so one block in your base layout covers the catalog. For products with options, extend `schema.html` into a `ProductGroup` with `hasVariant` entries that each carry their own SKU ([product variants](https://developers.google.com/search/docs/appearance/structured-data/product-variants)).

### 4. Link policy pages sitewide

Create web pages for returns, shipping, terms, privacy and contact. Then make sure your theme's footer links to all five on every page.

### 5. Turn on UCP when it's available to you

BigCommerce's UCP path is the Google agentic checkout program. It's in early access, and the article says timing is "subject to Google approval". It needs complete Merchant Center data: titles, GTINs, price, availability, shipping, a returns policy and a support contact ([BigCommerce](https://www.bigcommerce.com/articles/ecommerce/google-agentic-checkout/)). On **Catalyst**, version 1.12.0 proxies `/.well-known/ucp` and `/api/ucp/*` to BigCommerce, so agents find UCP on your own domain ([Catalyst 1.12.0 changelog](https://docs.bigcommerce.com/developer/changelog/2026/9/16)). If you customized `proxy.ts`, keep `withUcpProxy` first in `composeProxies`.

### 6. Give agents a cart link pattern

BigCommerce supports [add-to-cart URLs](https://docs.bigcommerce.com/developer/docs/admin/checkout-and-cart/custom-checkouts/add-to-cart-ur-ls) such as `/cart.php?action=add&product_id=123&qty=1`, and `action=buy` sends the shopper straight to checkout. Agents can't discover these on their own, so document the pattern in an `llms.txt` if you can serve one. The scan only gives full credit for a UCP permalink capability.

## Scan your store

[Run the free scan](https://is-agentic-storefront.com/) on your store URL to see which of these checks your theme passes. Every failing check comes with a fix prompt you can copy. Terms are defined in the [glossary](https://is-agentic-storefront.com/glossary).

## Sources

- [BigCommerce: Stencil tech stack](https://developer.bigcommerce.com/docs/storefront/stencil/start/tech-stack)
- [Cornerstone `schema.html`](https://github.com/bigcommerce/cornerstone/blob/master/templates/components/products/schema.html)
- [Cornerstone PR #2138: microdata to JSON-LD](https://github.com/bigcommerce/cornerstone/pull/2138)
- [BigCommerce: sitemaps](https://support.bigcommerce.com/s/article/Sitemaps)
- [BigCommerce: Catalyst sitemap](https://docs.bigcommerce.com/developer/docs/storefront/catalyst/content-management/sitemap)
- [BigCommerce: robots.txt file](https://support.bigcommerce.com/s/article/Understanding-the-Robots-txt-File)
- [BigCommerce: add-to-cart URLs](https://docs.bigcommerce.com/developer/docs/admin/checkout-and-cart/custom-checkouts/add-to-cart-ur-ls)
- [BigCommerce: Google agentic checkout](https://www.bigcommerce.com/articles/ecommerce/google-agentic-checkout/)
- [BigCommerce changelog: Catalyst 1.12.0 UCP proxy](https://docs.bigcommerce.com/developer/changelog/2026/9/16)
- [BigCommerce: `checkUcpProgram` mutation](https://docs.bigcommerce.com/developer/api-reference/graphql/admin/mutations/google-agentic-commerce/check-ucp-program)
- [Google: return policy structured data](https://developers.google.com/search/docs/appearance/structured-data/return-policy)
- [Google: product variants structured data](https://developers.google.com/search/docs/appearance/structured-data/product-variants)
- [UCP specification](https://ucp.dev/2026-08-25/specification/overview/)

## Frequently asked questions

### Does BigCommerce output Product structured data?

Recent versions of the Cornerstone theme output a Product JSON-LD block with SKU, MPN, GTIN, brand, price and availability. Older or custom themes may still use microdata or nothing at all.

### Where is the BigCommerce sitemap?

Stencil stores serve a dynamically generated XML sitemap at /xmlsitemap.php. Catalyst serves it at /sitemap.xml and redirects /xmlsitemap.php there.

### Does BigCommerce support UCP?

Partly. BigCommerce offers "Agentic Checkout with Google UCP" in early access through Commerce AI Labs, and Catalyst 1.12.0 proxies /.well-known/ucp to the platform. Whether your storefront returns a profile depends on enrollment, so scan it to check.

### How do I edit robots.txt on BigCommerce?

Go to Settings → Website → Search Engine Robots. BigCommerce merges your rules with its system defaults.

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---

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