example.com

robots.txt not found (HTTP 404)

How to fix: Publish /robots.txt with User-agent rules for AI crawlers (GPTBot, ClaudeBot, PerplexityBot, Google-Extended).

sitemap.xml not found (HTTP 404)

How to fix: Publish /sitemap.xml — Shopify/Hydrogen generates this automatically.

No hreflang link tags on the homepage.

How to fix: Add <link rel="alternate" hreflang="…"> tags for each supported locale plus x-default. Agents use these to pick the right regional storefront.

{
  "langs": []
}
                      

llms.txt not found.

How to fix: Publish /llms.txt summarizing your store, key products, and policies — agents use this as a quick index.

Server returned text/html despite Accept: text/markdown.

How to fix: Offer a Markdown variant of key pages — agents prefer Markdown over HTML when reading and summarizing pages.

{
  "contentType": "text/html",
  "status": 200
}
                      

Couldn't sample a product page from /sitemap.xml.

How to fix: Publish a sitemap that lists product URLs (Shopify/Hydrogen generates this automatically at /sitemap.xml).

Couldn't sample a product page to inspect variants.

How to fix: Ensure your sitemap exposes product URLs and that each product page renders Product JSON-LD with offers.

Couldn't sample a product page to inspect social meta tags.

How to fix: Ensure your sitemap exposes product URLs so social/agent crawlers can find them.

GET /cart → 404. GET /cart/000:1 → 404.

How to fix: Publish a /cart route that returns 200. Shopify/Hydrogen does this by default.

{
  "cartStatus": 404,
  "permalinkStatus": 404
}
                      

GET /checkout → 404. No handoff route detected.

How to fix: Expose a stable /checkout URL so agents can hand off a session — Shopify provides this out of the box; custom storefronts must wire it explicitly.

{
  "status": 404
}
                      

No UCP profile found. Last error: HTTP 404.

How to fix: Publish a UCP profile at /.well-known/ucp (Shopify stores get this automatically on Hydrogen/Online Store) and link to it from your homepage.

{
  "lastError": "HTTP 404",
  "triedLink": false
}
                      

No MCP server card at any well-known path. Last error: /.well-known/mcp-server-card.json: HTTP 404.

How to fix: Publish a server card at /.well-known/mcp/server-card.json with name, remotes[], and capabilities. See SEP-2127.

{
  "lastError": "/.well-known/mcp-server-card.json: HTTP 404",
  "triedPaths": [
    "/.well-known/mcp/server-card.json",
    "/.well-known/mcp-server-card.json"
  ]
}
                      

/checkout_sessions returned 404.

How to fix: Implement the ACP checkout sessions endpoint. Stripe's docs/agentic-commerce has a turnkey integration for merchants.

{
  "status": 404,
  "hasLink": false
}
                      

Probe https://example.com/.well-known/x402 returned 404; no x402 signal.

How to fix: Adopt x402 by responding with 402 + PAYMENT-REQUIRED header on a gated route, or publish a manifest at /.well-known/x402.

{
  "probeUrl": "https://example.com/.well-known/x402",
  "status": 404
}
                      

WebMCP signals — header:false, meta:false, script-src:false, inline-register:false, inline-mention:false.

How to fix: Opt into WebMCP: register tools with navigator.modelContext.registerTool(...) in an inline <script>, or set the WebMCP-Available: true response header.

{
  "headerSignal": false,
  "metaSignal": false,
  "scriptSrcSignal": false,
  "inlineRegisterSignal": false,
  "inlineMentionSignal": false
}