These three terms are being used in the same conversations, but they sit at different layers.
This article is part of Nyansa Hub’s Amazon Seller AI Agent series, built for sellers who want useful AI without handing over unrestricted authority.
SP-API
Selling Partner API is Amazon's programmatic interface for seller data and actions. Applications use roles/authorization to access specific capabilities.
MCP
Model Context Protocol is a general way for AI clients to discover and call tools. An MCP server can expose tools that internally call SP-API. MCP is not Amazon authorization and is not your business permission policy.
Selling Partner plugin
Amazon's new Selling Partner plugin is a supported integration surface designed to make seller capabilities available inside agentic environments such as Amazon Quick and, in beta, Claude.
Which should a seller use?
If you want the supported plug-and-play path inside a compatible AI environment, the plugin may be the most direct. If you are building custom developer workflows, Amazon's SP-API and Local MCP examples are relevant. If you want a local seller-controlled architecture, you can build the connector/control layer around SP-API and optionally expose narrow tools through MCP.
The more important choice is the authority model around whichever connection you select. A plugin can be official and still deserve seller-defined approval rules. An MCP server can be local and still be unsafe if it exposes unrestricted tools. Direct SP-API code can be robust or reckless depending on the controls around it.
Connector choice is architecture. Permission choice is governance. Do not confuse the two.
Where to go next
Use the Playbook if you are deciding which architecture fits. Use the Coding Build Kit when you are ready to implement a local control layer.
Put this into practice
Use the Amazon Seller AI Agent Playbook to choose the connection architecture. When you are ready to implement a local control layer, move to the Secure Local Amazon Seller AI Agent Coding Build Kit.
Sources and current references
- Amazon Accelerate 2026: Seller Assistant workflows + Selling Partner plugin
- Amazon BSA / Agent Policy update
- SP-API onboarding and roles
- Amazon SP-API samples / Local MCP
- Amazon Ads FAQ
Browse the full Amazon Seller AI Agents resource family for the related quick tools, recurring operating resources, and technical implementation options.