Shopify API + MCP vs Vendure

Shopify API + MCP

Typed GraphQL schemas with quarterly versions supported at least 12 months. Closed platform. You can't self-host or change checkout internals.

Vendure

Full cart, coupon, shipping and payment flow in the GraphQL Shop API, with ErrorResult types an agent can branch on. No vendor-hosted API. Vendure Cloud is only partly available.

Shopify API + MCP

1. Pin an API version in the URL and plan to move at least once a year. Old versions fall forward to the oldest supported one
2. Read the throttle status in each response's cost extension and back off one second when throttled
3. Send an agent profile in meta on every UCP call, and an idempotency key on every checkout write
4. Check userErrors on every mutation. A 200 response can still carry a failed write
5. Add @shopify/dev-mcp while writing code so the agent checks queries against the current schema

Vendure

1. Keep the session token from the first Shop API response and send it on every call. It holds the active order
2. Check each mutation result's __typename and errorCode. Expected failures return 200 with an ErrorResult
3. Don't retry addItemToOrder blindly. Read the active order first, since a repeat adds the quantity again
4. For server-side work, enable api-key in authOptions.tokenMethod and give the key one role in one channel
5. Run 3.7.3 or later, and purge old job records, which may still hold session tokens