Elastic Path API + MCP vs Spree Commerce

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.

Spree Commerce

A self-hosted BSD 3-Clause platform with public OpenAPI files for the Store and Admin APIs, scoped secret keys, documented rate limits and idempotency keys on cart and checkout calls. GitHub lists six security advisories between January and July 2026, four rated High, and the default docs describe the 6.0 release candidate while 5.6.1 is the stable release.

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

Spree Commerce

1. Send a publishable key in X-Spree-Api-Key on every Store API call. Add X-Spree-Token with the cart token for guest carts, or a customer JWT as a Bearer token
2. Send Idempotency-Key with the cart token or a customer JWT on cart, payment and completion calls. A request carrying only the publishable key is never cached
3. Ask for fields and expand explicitly. Relations are left out by default and limit stops at 100
4. Use a secret key with the narrowest scopes for the Admin API. read_all gives a read-only key, and the CLI's auto-minted local key is read-only
5. Read the docs under /docs/v5 for a 5.6 store. The default docs describe 6.0, which renames shipments to fulfilments and splits carts from orders