Agentzon vs Elastic Path API + MCP

Agentzon

Public OpenAPI 3.1 description and llms.txt, with a whole-basket checkout that needs no account or key. The buyer pays on a private page, so a person completes each purchase. No status page, security.txt or registered seller address was found on agentzon.co, and 34 of 500 listed items cannot be bought.

Elastic Path API + MCP

Cart, promotion code, checkout and order endpoints cover the whole test flow. MCP server exposes 95 tools with full CRUD, no read-only mode and no public source or licence.

Agentzon

1. Search with GET /api/products. Use only items with checkoutAvailable true and a non-null unitAmount, because a null price means unavailable, never free
2. Send every item and quantity in one POST /api/checkout, with a new Idempotency-Key for each purchase attempt and the same key only to retry that basket
3. Show the buyer the product image from /api/products/{id}/image and get their approval before opening the checkout URL
4. Tell the buyer that catalogue prices exclude sales tax, that shipping is U.S. only and that change-of-mind returns exclude hygiene and food items
5. Keep the checkout URL and the orderToken private. A paid status confirms payment, not shipment

Elastic Path API + MCP

1. Use a client_credentials token server-side only. It has full CRUD on the store
2. Pick the base URL for the store's region (useast or euwest), or every call returns 401
3. Loading the MCP server costs 95 tool definitions, so enable it only for agents that need the back office
4. On a 429, wait a few seconds and retry. No Retry-After header is sent
5. Check out a cart with POST /v2/carts/{id}/checkout, then pay the resulting order