Agentzon vs BigCommerce 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.

BigCommerce API + MCP

Published rate limits per plan, with X-Rate-Limit-Time-Reset-Ms on every 429. Storefront MCP is beta, switched on per store, has no back-office tools and documents no tool annotations.

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

BigCommerce API + MCP

1. Give the agent a store-level API account with only the scopes the task needs, and delete it when done
2. On a 429, wait X-Rate-Limit-Time-Reset-Ms before retrying
3. Expect up to 10 minutes after a store owner enables the MCP before the URL answers
4. The MCP stops at a checkout URL. Payment happens in the shopper's browser
5. Point a coding agent at the docs MCP at https://docs.bigcommerce.com/_mcp/server