UCP Checker
UCP Score

UCP Score for littleshoes.cz

Ready for UCP agents

88 out of 100, grade A: ready for UCP agents. The missing 12 points are spread across Discovery and Conformance and Capabilities. 2 spec breaks on the status page aren't counted in the score.

Discovery 95Conformance 88Capabilities 81release 2026-08-25

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).
95−1.5 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.
88−4.8 pts
Capabilities 30%
What an agent can do here: how many capabilities, checkout, at least one service, payment handlers, and services that answer our check.
81−5.7 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
+5
1Publish the public keys agents use to check your messages
Your UCP profile lists no public keys, so an agent cannot confirm that a message really came from your store.
Agents use these keys to check that checkout messages really came from you. A store that takes payment through the agent needs them. A store that sends the buyer to its own checkout page can manage without them for now.
Conformance · effort medium
{
  "keys": [
    {
      "kty": "EC",
      "crv": "P-256",
      "x": "<base64url x>",
      "y": "<base64url y>",
      "kid": "store-2026-10",
      "use": "sig",
      "alg": "ES256"
    }
  ],
  "ucp": { ... }
}

Create a P-256 (ES256) key pair: ES256 is the one algorithm every UCP agent must be able to check. Add the public key to a "keys" list at the top level of your UCP profile, as in the example, with its own "kid", and keep the private key on your server. The spec recommends a new key every 90 days: publish the new one next to the old, sign with it, and remove the old key a week later.

+2
2Publish 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.

Every check

12 passed · 4 to fix
Agent Discovery · 7 of 8
7 OK
HTTPS, UCP profile reachable, AI bot access, sitemap.xml, Open Graph tags, Organization schema (JSON-LD), Mobile viewport metaShow
  • HTTPS · Profile URL uses https://
  • UCP profile reachable · HTTP 200
  • AI bot access · robots.txt allows /.well-known/ucp
  • sitemap.xml · Found at /sitemap.xml
  • Open Graph tags · og:title and og:type/url present
  • Organization schema (JSON-LD) · Organization-typed JSON-LD detected
  • Mobile viewport meta · <meta name="viewport"> present
Problem
llms.txt
HTTP 200 at /llms.txt. Fix 2 above.
Discovery
UCP Conformance · 2 of 4
2 OK
Profile passes schema validation, Protocol version present and well-formedShow
  • Profile passes schema validation · No structural errors
  • Protocol version present and well-formed · Version: 2026-08-25
To fix
Public keys published
No keys list at the top level of the profile. Fix 1 above.
Conformance
To fix
No validation warnings
1 warning.
Conformance
Capability Coverage · 3 of 4
3 OK
Capabilities declared, Checkout capability, Transports declaredShow
  • Capabilities declared · 3 of 6 capability families detected: Checkout, Cart Management, Catalog. A family counts once however many namespaces or extensions declare it.
  • Checkout capability · dev.ucp.shopping.checkout detected
  • Transports declared · REST
To fix
Payment handlers
Empty array: checkout-link redirect strategy.
Capabilities

Not in the score, but worth fixing first

spec breaks
Problem
The profile sits behind a redirect
littleshoes.cz/.well-known/ucp answers 301 redirect. The spec forbids redirects on the profile, so an agent that asks littleshoes.cz stops there. Serve it directly on every host agents use.
on the status page
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.

Speed among Shoptet stores
The profile answered in 635 ms, faster than 93% of the Shoptet stores we check.