What does a 401 response from the MCP endpoint mean?
The request has not established valid client authentication. Follow OAuth discovery and sign-in for OAuth clients, or use a properly scoped bearer token in a compatible client. Do not paste the Amazon refresh token into a prompt.
What does an access-denied response after login mean?
Check workspace membership, active entitlement, token scopes and seller authorization. Login alone does not grant paid features. A correct multi-tenant service should deny a request for another customer's seller data.
Should I select SSE or Streamable HTTP?
Use the transport the server actually implements. EzSeller exposes its remote MCP endpoint at /mcp and uses HTTP requests; do not infer a legacy SSE endpoint merely because a client offers an SSE option.
Does a successful tools/list call prove the integration works?
No. Verify a permitted tool call, the correct tenant and seller, a real upstream response and the resulting evidence. Repeat after cancellation to confirm that access follows the configured billing lifecycle.
Sources and further reading
Guide coverage is not a claim that every workflow is enabled in the trial. Check the live tool catalog, your permissions, and the source evidence. Unknown data stays unknown.