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UCP Score

UCP Score for gtslotcars.com

Ready for UCP agents

87 out of 100, grade A: ready for UCP agents. The missing 14 points are spread across Discovery and Capabilities. One spec break on the status page isn't counted in the score.

Discovery 75Conformance 100Capabilities 80release 2026-04-08

UCP Score 87/100 grade A · ready for UCP agents
Points missing 14 Discovery, Capabilities Fixes 7 raise the score Spec breaks 1 not in the score

How the score is made

three areas, weighted
Discovery 30%
Can a UCP agent find and read the profile: HTTPS, an answer at /.well-known/ucp, robots.txt allowing it, and five files outside UCP (llms.txt, sitemap, Open Graph, Organization schema, viewport).
75−7.5 pts
Conformance 40%
Does the profile follow the spec: valid against its release (counted three times), a dated release, keys published, few warnings, spec and schema links that resolve.
100full marks
Capabilities 30%
What an agent can do here: how many capabilities, checkout, at least one service, payment handlers, and services that answer our check.
80−6 pts
A85–100Ready for UCP agents
B70–84Nearly there
C50–69Partly ready
D30–49Hard for UCP agents
F0–29Not ready

Raise the score

fixes that move the number
+6
1Repair declared transport endpoints
One or more declared transport endpoints did not respond when probed.
A declared endpoint that does not answer stops an agent at that step, even though the profile itself validates. Connection refused, DNS failure, TLS errors, and 5xx responses all fall here. See the Full Check Breakdown below for the specific endpoints that failed.
Capabilities · effort medium
part of +8
2Publish Organization schema (JSON-LD) on the homepage
No Organization-typed JSON-LD detected on your homepage.
Organization schema gives agents a structured representation of your brand identity: name, logo, social profiles, contact info, founding date. Agents use this to verify you are who you claim to be and to link your profile data to a recognizable entity.
Discovery · effort medium 
<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "OnlineStore",
  "name": "Yourstore",
  "url": "https://yourstore.com",
  "logo": "https://yourstore.com/logo.png",
  "sameAs": [
    "https://twitter.com/yourstore",
    "https://www.instagram.com/yourstore"
  ],
  "contactPoint": {
    "@type": "ContactPoint",
    "telephone": "+1-800-000-0000",
    "contactType": "Customer Service"
  }
}
</script>

Drop into <head> or end of <body>. Use OnlineStore (more specific) when the entire site is an ecommerce store; Organization is the generic fallback.

To fix
3Move to the latest UCP protocol version
Your profile declares a valid but older protocol version. A newer one is published.
Older versions stay valid (agents use the version you declare), but newer abilities (embedded checkout, agent payment mandates, linked customer accounts, card authentication, payment terms and store location lookup) only work against the latest version. The profile itself barely changes: the signing keys move to a root-level "keys" list, and the rest of the update is in what capabilities can say.
Conformance · effort low 
"ucp": {
  "version": "2026-08-25",
  ...
},
"keys": [ ... ]   // beside "ucp", not inside it

Set the version to 2026-08-25 and publish your public keys as a root-level "keys" list. The older "signing_keys" field is still accepted, but "keys" is the one every verifier reads.

part of +8
4Publish a /llms.txt brand brief
No /llms.txt file detected at the root of your domain.
llms.txt is an emerging convention (analogous to robots.txt) that lets you give AI agents a hand-written brief about your brand, product categories, return policy, and crawl preferences. Strict UCP agents do not require it, but recommendation/discovery agents increasingly read it for context.
Discovery · effort low 
# llms.txt
# Public brief for AI agents about Yourstore

# About
One or two sentences on what you sell, who you sell to, and any defining context (founded, mission, sustainability stance, etc.).

# Product Categories
- Category one
- Category two
- Category three

# Policies
- Returns: e.g. 30 days, full refund
- Shipping: e.g. Free over $30, 3-5 business days
- Any other policy worth surfacing (cruelty-free, vegan, made-to-order, etc.)

# Agent Capabilities
- UCP profile: /.well-known/ucp
- Supported flows: cart, checkout, tokenized payment, etc.
- Anything explicitly NOT supported (e.g. "no subscription products via agent")

# Contact
[email protected]

Save as /llms.txt at your site root. Plain text, written for an LLM audience. The format is informal: these section headings are a working convention, not a spec. Replace the placeholders with your own brand details and update when policies or product lines change.

part of +8
5Publish a sitemap.xml
No sitemap.xml detected at the root of your domain.
Sitemaps tell agents and crawlers which pages on your store are canonical and how often they change. Without one, agents fall back to following internal links, which is slower and less complete, especially for catalog pages buried behind faceted nav.
Discovery · effort low 
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://yourstore.com/</loc>
    <changefreq>daily</changefreq>
  </url>
  <url>
    <loc>https://yourstore.com/products</loc>
    <changefreq>daily</changefreq>
  </url>
  <!-- one <url> entry per indexable page -->
</urlset>

Most ecommerce platforms generate sitemap.xml automatically. If yours does not, generate one and serve it at /sitemap.xml.

part of +8
6Add Open Graph meta tags to the homepage
OG tags missing or incomplete on your homepage.
OG tags give agents and link unfurlers (Slack, iMessage, ChatGPT) a clean title, description, and image to represent your store. Without them, shares show garbled fallback text.
Discovery · effort low 
<meta property="og:title" content="Yourstore | short tagline">
<meta property="og:type" content="website">
<meta property="og:url" content="https://yourstore.com/">
<meta property="og:description" content="One-sentence description of what you sell.">
<meta property="og:image" content="https://yourstore.com/og-cover.jpg">
<meta property="og:site_name" content="Yourstore">

Add inside <head>. og:title and og:type are the minimum; og:url, og:description, and og:image are strongly recommended.

part of +8
7Add a mobile viewport meta tag
No viewport meta tag detected on your homepage.
Mobile-originating agent sessions (ChatGPT iOS, Apple Intelligence) render store pages in browser sandboxes that respect the viewport tag. Without it, the page renders at desktop width and pinch-to-zoom UX kicks in, and agents that take screenshots of pages get unreadable images.
Discovery · effort low 
<meta name="viewport" content="width=device-width, initial-scale=1">

One line inside <head>. Modern frontend frameworks add this automatically; its absence usually means a hand-rolled or legacy template.

Every check

12 passed · 7 to fix
Agent Discovery · 3 of 8
3 OK
HTTPS, UCP profile reachable, AI bot accessShow
  • HTTPS · Profile URL uses https://
  • UCP profile reachable · HTTP 200
  • AI bot access · robots.txt allows /.well-known/ucp
Problem
llms.txt
HTTP 404 at /llms.txt. Fix 4 above.
Discovery
Problem
sitemap.xml
HTTP 403 at /sitemap.xml. Fix 5 above.
Discovery
Problem
Open Graph tags
Missing or incomplete on homepage. Fix 6 above.
Discovery
Problem
Organization schema (JSON-LD)
Missing or incomplete on homepage. Fix 2 above.
Discovery
Problem
Mobile viewport meta
Missing or incomplete on homepage. Fix 7 above.
Discovery
UCP Conformance · 5 of 5
5 OK
Profile passes schema validation, Protocol version present and well-formed, Public keys published, No validation warnings, Spec & schema URLs resolve (11)Show
  • Profile passes schema validation · No structural errors
  • Protocol version present and well-formed · Version: 2026-04-08
  • Public keys published · Keys published at the top level
  • No validation warnings · No outstanding validation issues
  • Spec & schema URLs resolve (11) · All 11 URLs resolved.
Capability Coverage · 4 of 6
4 OK
Capabilities declared, Checkout capability, Transports declared, Payment handlersShow
  • Capabilities declared · 3 of 6 capability families detected: Checkout, Cart Management, Order Management. A family counts once however many namespaces or extensions declare it.
  • Checkout capability · dev.ucp.shopping.checkout detected
  • Transports declared · REST, MCP
  • Payment handlers · 1 handler registered
To fix
REST transport reachable
Host responded with HTTP 403 — endpoint reachable but path may be method-restricted.
Capabilities
Problem
MCP transport reachable
HTTP 403 on tools/list.
Capabilities

Not in the score, but worth fixing first

spec breaks
To fix
The profile has no ETag or Last-Modified header
Spec level: SHOULD. Not part of the UCP Score.
on the status page

The score measures what the profile declares across the three areas above. These break a rule in the spec that agents follow, so they can stop an agent before the score matters.

Files for agents

outside UCP · not part of the UCP Score

Files gtslotcars.com publishes for agents beyond its UCP profile, from our weekly look. Only what we found is listed.

Found
API catalog /.well-known/api-catalog
Lists the store's APIs (RFC 9727).
16 Oct
Found
MCP server card /.well-known/mcp/server-card.json
Describes the store's MCP server before an agent connects.
15 Oct
Found
A2A agent card /.well-known/agent-card.json
Describes the store's own agent, for agent-to-agent calls.
13 Oct
Found
Signatures directory /.well-known/http-message-signatures-directory
Keys for agents that sign their requests (Web Bot Auth).
13 Oct
Found
Agent skills /.well-known/agent-skills/index.json
Ready-made instructions an agent can load to work with the store.
product-searchcart-management
11 Oct
Found
ai-catalog.json /.well-known/ai-catalog.json
The earlier name for the ARD catalogue.
11 Oct
/.well-known/api-catalog as served 407 B 
{
  "linkset": [
    {
      "anchor": "https://gtslotcars.com/api",
      "service-desc": [
        {
          "href": "https://developer.bigcommerce.com/openapi-specs/catalog-v3.yaml",
          "type": "application/vnd.oai.openapi"
        }
      ],
      "service-doc": [
        {
          "href": "https://developer.bigcommerce.com/docs",
          "type": "text/html"
        }
      ]
    }
  ]
}
/.well-known/mcp/server-card.json as served 481 B 
{
  "$schema": "https://modelcontextprotocol.io/schemas/server-card/v1.0",
  "version": "1.0",
  "protocolVersion": "2025-06-18",
  "serverInfo": {
    "name": "GT Slot Cars MCP",
    "version": "1.0.0",
    "description": "Provides tool access to the GT Slot Cars catalog and cart management."
  },
  "transport": {
    "type": "streamable-http",
    "url": "https://gtslotcars.com/mcp"
  },
  "capabilities": {
    "tools": true,
    "resources": true,
    "prompts": false
  }
}
/.well-known/agent-card.json as served 946 B 
{
  "name": "GT Slot Cars Assistant",
  "version": "1.0.0",
  "description": "An automated agent for browsing the GT Slot Cars catalog and managing shopping carts.",
  "supportedInterfaces": [
    {
      "url": "https://gtslotcars.com/mcp",
      "protocolBinding": "JSONRPC",
      "protocolVersion": "1.0"
    }
  ],
  "capabilities": {
    "streaming": false,
    "pushNotifications": false
  },
  "skills": [
    {
      "id": "product-search",
      "name": "Product Search",
      "description": "Searches the GT Slot Cars catalog for vehicles, tracks, and parts."
    },
    {
      "id": "cart-management",
      "name": "Cart Management",
      "description": "Adds or removes items from the user's shopping cart."
    }
  ],
  "extensions": [
    {
      "uri": "https://github.com/google-agentic-commerce/AP2/tree/v0.1.0",
      "required": true,
      "params": {
        "roles": [
          "merchant"
        ]
      }
    }
  ]
}
/.well-known/http-message-signatures-directory as served 163 B 
{
  "keys": [
    {
      "kty": "OKP",
      "crv": "Ed25519",
      "x": "11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPPRWQI",
      "kid": "example-key-id"
    }
  ]
}
/.well-known/agent-skills/index.json as served 713 B 
{
  "$schema": "https://schemas.agentskills.io/discovery/0.2.0/schema.json",
  "skills": [
    {
      "name": "product-search",
      "type": "skill-md",
      "description": "Searches the GT Slot Cars catalog for vehicles and parts.",
      "url": "https://gtslotcars.com/skills/product-search/SKILL.md",
      "digest": "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    },
    {
      "name": "cart-management",
      "type": "skill-md",
      "description": "Adds or removes items from the customer's cart.",
      "url": "https://gtslotcars.com/skills/cart-management/SKILL.md",
      "digest": "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    }
  ]
}
/.well-known/ai-catalog.json as served 1.4 KB 
{
  "specVersion": "1.0",
  "host": {
    "name": "GT Slot Cars",
    "description": "High-quality 1:32 scale slot cars, tracks, tuning parts, and accessories."
  },
  "entries": [
    {
      "id": "urn:air:gtslotcars.com:mcp:server",
      "displayName": "GT Slot Cars MCP Server",
      "type": "application/json",
      "url": "https://gtslotcars.com/.well-known/mcp/server-card.json",
      "representativeQueries": [
        "Search the GT Slot Cars product catalog using MCP",
        "Connect to GT Slot Cars Model Context Protocol server",
        "Find 1:32 scale slot cars via MCP tool"
      ]
    },
    {
      "id": "urn:air:gtslotcars.com:a2a:agent",
      "displayName": "GT Slot Cars A2A Agent",
      "type": "application/json",
      "url": "https://gtslotcars.com/.well-known/agent-card.json",
      "representativeQueries": [
        "Interact with the GT Slot Cars A2A agent",
        "Add items to GT Slot Cars shopping cart automatically",
        "Browse GT Slot Cars using agentic protocol"
      ]
    },
    {
      "id": "urn:air:gtslotcars.com:api:checkout",
      "displayName": "GT Slot Cars Checkout API",
      "type": "application/json",
      "url": "https://gtslotcars.com/openapi.json",
      "representativeQueries": [
        "Process payment for GT Slot Cars",
        "Submit an order to GT Slot Cars API",
        "Review GT Slot Cars checkout OpenAPI schema"
      ]
    }
  ]
}
Speed among Bigcommerce stores
The profile answered in 422 ms, faster than 26% of the Bigcommerce stores we check.