generated: '2026-07-17'
method: searched
source: https://99counties.com/llms.txt
summary: >-
  99 Counties is a Shopify storefront that exposes an agent-native commerce surface via
  the Universal Commerce Protocol (UCP) over MCP, plus the standard Shopify read-only JSON
  endpoints. These are the cross-cutting conventions an agent must follow.
authentication:
  browsing: none (unauthenticated read-only)
  customer_account: Shopify Customer Account OAuth 2.0 / OIDC (PKCE S256)
  ref: authentication/99-counties-authentication.yml
agent_commerce:
  protocol: UCP (Universal Commerce Protocol)
  discovery: GET https://99counties.com/.well-known/ucp
  mcp_endpoint: POST https://99counties.com/api/ucp/mcp
  flow:
  - discover (GET /.well-known/ucp)
  - search (search_catalog)
  - cart (create_cart)
  - checkout (create_checkout)
  - fulfill (update_checkout — shipping address + method)
  - complete (complete_checkout — buyer must approve payment)
  buyer_approval: >-
    Checkout requires contemporaneous human approval. Agents must not complete payment
    without explicit buyer consent. Where approval cannot be obtained at the moment of
    payment, route via the Shop skill (https://shop.app/SKILL.md) through Shop Pay.
  buyer_context:
  - context.address_country
  - context.currency
read_only_browsing:
  products_all: GET /collections/all
  product_page: GET /products/{handle}
  product_json: GET /products/{handle}.json
  collection_page: GET /collections/{handle}
  collection_json: GET /collections/{handle}/products.json
  search: GET /search?q={query}&type=product
  sitemap: GET /sitemap.xml
rate_limiting:
  documented: true
  scope: per-IP on the UCP MCP endpoint
  signal: HTTP 429
  guidance: back off on 429 responses
idempotency:
  documented: false
  note: No idempotency-key contract is published for the storefront/UCP surface.
error_handling:
  mcp_envelope: JSON-RPC 2.0 error object (e.g. code -32001, data.code invalid_profile_url)
  ref: conformance/99-counties-conformance.yml
payment_handlers:
- com.google.pay (Google Pay)
- dev.shopify.card (card)
- dev.shopify.shop_pay (Shop Pay)
cross_links:
  authentication: authentication/99-counties-authentication.yml
  scopes: scopes/99-counties-scopes.yml
  well_known: well-known/99-counties-well-known.yml
  mcp: mcp/99-counties-mcp.yml