Since May 29, 2026, every Shopify store serves a default /agents.md file, with /llms.txt and /llms-full.txt both pointing at the same content. This is platform-level, not opt-in — a merchant who never touched the setting has one today. It changes what an llms.txt app or service can actually do on Shopify, and what a merchant paying for one is actually paying for now.
What changed
Shopify's own developer changelog dates the change to May 28–29, 2026: shopify.dev/changelog/customize-llmstxt-llms-fulltxt-and-agentsmd. Before that, the three paths either didn't exist or were open for arbitrary customization by whatever route a merchant or app used. After it, Shopify's help documentation states plainly: "Your store includes a default agents.md file accessible at /agents.md. The paths /llms.txt and /llms-full.txt also point to this content by default."
agents.md is the canonical file. Shopify's own description of it, from the theme architecture docs, calls it "the canonical, agent-facing description of a store" — containing UCP (Universal Commerce Protocol) discovery endpoints, MCP details, and commerce capabilities, populated automatically per store. /llms.txt and /llms-full.txt aren't independent files; they mirror whatever /agents.md resolves to, unless a merchant overrides one of them specifically.
We checked this against a live, apparently-uncustomized store: the default content opens with agent instructions specific to that store's name and domain, recommends installing Shopify's own shop.app/SKILL.md for personal shopping agents, documents the store's UCP discovery endpoint (/.well-known/ucp) and MCP endpoint (/api/ucp/mcp), and closes with a line describing Shopify as "the commerce platform powering millions of stores worldwide." That phrasing is boilerplate, not a description any merchant wrote — the tell that a given store's file is still running the unmodified default.
What still works: theme-level customization
Shopify's docs describe exactly one supported customization path, and it isn't an app or a redirect. A merchant (or a developer working in the store's code editor) can add up to three optional Liquid templates under Online Store > Themes > Edit code:
| Template | Controls |
|---|---|
templates/agents.md.liquid | /agents.md, and the fallback for the other two paths if they don't have their own template |
templates/llms.txt.liquid | /llms.txt only |
templates/llms-full.txt.liquid | /llms-full.txt only |
If only agents.md.liquid exists, it's used for all three URLs. Adding a dedicated llms.txt.liquid or llms-full.txt.liquid makes that one path diverge from agents.md while the others keep mirroring it. If none of the three templates exist, the fallback chain runs agents.md.liquid → the Shopify-generated default — so there's never a 404, only ever "your content" or "the generic default."
One real constraint worth knowing before hand-editing this file: agents.md.liquid runs with a restricted Liquid context. Shopify's own template docs note that "the standard global Liquid objects aren't injected, so they render blank," including shop, articles, blogs, collections, pages, and linklists. The template gets a dedicated agents object instead (store name, URLs, UCP versions, currency, and similar), and a merchant writing custom content here needs to work from that object, not the theme objects used everywhere else on the storefront. Whoever edits this file also takes on keeping it current — Shopify's docs are explicit that it's an unsupported customization, the same status as robots.txt.liquid has always had.
robots.txt itself is unaffected by any of this. It remains editable only through a theme's own robots.txt.liquid, exactly as before — a separate system from the three agent-discovery paths above.
What this means for merchants
If a store has never touched these paths, it already has an /agents.md. There's nothing to install to get one. What it has is Shopify's generic default — accurate about UCP endpoints and generic commerce guidance, but not a description of that specific store, its policies, or anything a merchant would want an AI agent to know that goes beyond the platform boilerplate.
Product data reaching AI shopping assistants is a separate system, and it's also automatic. Since Shopify Catalog began syndicating eligible product data (titles, pricing, availability, images) to agentic storefronts like ChatGPT and Microsoft Copilot in early 2026, that pipeline runs independently of both robots.txt and the agents.md/llms.txt files — a merchant doesn't need to configure either to have products appear there. What robots.txt and crawler access still govern is different: whether a buying guide, category page, FAQ, or blog post — the content types that actually earn a citation inside an AI-generated answer, as opposed to a structured product listing — is reachable and readable by AI crawlers at all.
What's worth reconsidering paying for. Before May 2026, a tool that generated and served /llms.txt for a Shopify store was doing something the platform didn't do on its own. That's no longer true for the base case — every store has the file already. What a tool can still legitimately do is help write and maintain the content of a templates/agents.md.liquid override: a real description of the store, in a format an agent can use, instead of the generic default. That's a narrower, more specific service than "generates llms.txt," and it's worth asking directly whether a given app or service does that, or whether it's still describing itself as solving a problem Shopify solved platform-wide three months ago.
Sources
- Shopify developer changelog: Customize /llms.txt, /llms-full.txt and /agents.md
- Shopify theme architecture docs: agents.md.liquid
- Shopify Help Center: Shopify Catalog and product discovery for agentic storefronts
- Shopify Help Center: Editing robots.txt.liquid
Check where a store actually stands
Run a free scan against any Shopify store's URL — it checks whether llms.txt is present and flags when it's still Shopify's unmodified platform default rather than something specific to that store, alongside crawler access, structured data, and content readability. See CrawlPod for Shopify for what's checked in more depth, or the llms.txt glossary entry for what the file is for in the first place.