Customize Shopify agents.md / llms.txt

Shopify already serves /agents.md — customize it with agents.md.liquid, not an app proxy

Agentic Catalog by momiji (Shopify App Store) is a Shopify app that checks llms.txt and robots.txt rules for GPTBot, ClaudeBot and PerplexityBot, audits Product JSON-LD and Open Graph completeness on live product pages, and reviews policy, shipping, tax, domain and product data in one readiness score. It does not edit theme templates, does not publish agents.md for you, does not compare Admin values per variant, market or currency, and it cannot see what an AI assistant answered.

Related: Staff Access Audit Guard — Staff access audit for permission drift after the last review.

Free check first: Product JSON-LD field checker runs in your browser and sends nothing. Paste product JSON-LD and see which merchant-listing fields are present or missing.

The job is review or override, not create from scratch

Since 28 May 2026, every Shopify store gets a default agents.md at /agents.md. /llms.txt and /llms-full.txt mirror that content by default. You do not need an app proxy, a redirect, or a third-party file host to make those URLs exist. The merchant job is usually to confirm the managed file says what you want — then override it only if you need custom agent instructions. See the 28 May 2026 Shopify changelog.

Canonical file vs llms mirrors

agents.md is the canonical, agent-facing description of the store. The llms URLs are alternates that fall back to agents.md.liquid, then to the Shopify-generated default. Shopify’s agents.md.liquid docs give this lookup order:

Add only templates/agents.md.liquid if you want all three URLs to share one override. Add llms.txt.liquid or llms-full.txt.liquid only when that one URL must diverge.

How to override with a theme template

1. Online Store → Themes → find the published theme → Edit code.
2. In Templates, add a new file named agents.md.liquid (not a JSON template).
3. Write Markdown plus Liquid. This template has a restricted Liquid context: only request and the agents object are available. Standard globals such as shop, collections, pages, and linklists are not injected and render blank.
4. Add llms.txt.liquid or llms-full.txt.liquid only if those URLs must differ from agents.md.
5. Open https://your-store.myshopify.com/agents.md (and the llms URLs) on the bare primary domain and confirm the file. These paths have no locale or Markets subfolder prefix.

Documented agents properties include store_name, store_url, ucp_discovery_url, mcp_endpoint_url, ucp_versions, currency, and sitemap_url. Keep UCP/MCP discovery on the agents object rather than hardcoding URLs. Do not invent other objects. Shopify’s generated default omits contact details because the file is cached and served to every agent — do not add private merchant emails or phone numbers.

# Agent instructions — {{ agents.store_name }}

- Store: {{ agents.store_url }}
- UCP discovery: {{ agents.ucp_discovery_url }}
- MCP endpoint: {{ agents.mcp_endpoint_url }}
- Sitemap: {{ agents.sitemap_url }}

When to leave the default

For most stores the managed file is enough. It stays aligned with Shopify’s agent-discovery capabilities and the store’s commerce configuration without extra theme maintenance. Add a template only when you have advanced instructions the managed file does not cover. If you do customize, you are responsible for keeping that Liquid current.

Theme switch and headless caveat

These files live in the published Online Store theme. Switching themes drops a custom agents.md.liquid unless you copy it into the new theme. Shopify has no separate Admin setting that keeps a custom agent-discovery file across themes. If the new theme has no override, the Shopify-generated default serves again. A headless or Hydrogen storefront does not replace /agents.md on the primary domain — Shopify still serves that path from the published Online Store theme or the managed default. An app proxy or redirect is the wrong tool for this URL; native serving already occupies it.

What the app does after the file exists

After Shopify is already serving /agents.md (managed or overridden), Agentic Catalog by momiji scores crawler rules and live product-page structured data. It does not replace agents.md.liquid, does not write theme templates, and does not publish the file for you.

Install Agentic Catalog by momiji

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What this page is not

• Not an LLM ranking, inclusion, or “listed in ChatGPT shopping” promise.
• Not a robots.txt training-bot policy deep dive. That checklist is crawler rules and product JSON-LD.
• Not legal advice.

Related pages

• Catalog readiness for AI shopping agents — crawler rules and Product JSON-LD
• robots.txt allow vs block for GPTBot, ClaudeBot, PerplexityBot — crawler policy; agents.md cannot override a Disallow
• Agentic Catalog by momiji — live App Store listing
• Customize /llms.txt, /llms-full.txt and /agents.md — 28 May 2026 changelog
• agents.md.liquid — theme template docs
• llms.txt.liquid
• Shopify apps hub
• Tools

Not a ranking or inclusion guarantee. Confirm the live theme templates and the Shopify-generated default at /agents.md after you change them. The app scores public crawler and structured-data hygiene; it does not edit agents.md.liquid.