MCP Server vs REST API

Closient exposes the same product graph through two surfaces: a hosted Model Context Protocol server and an HTTPS REST API. They cover the same data; they’re optimised for different consumers.

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Should I use the MCP server or the REST API?

The rough rule: if the consumer is an LLM, use MCP. If the consumer is code you wrote, use REST.

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What’s the difference between an AI agent calling MCP and an AI agent calling the REST API?

Both work; the AI client experience is what differs. MCP gives the agent a tool list at connect time, with structured input/output schemas and human-readable descriptions. The agent picks tools by name and the LLM doesn’t need any “how to call this API” documentation in its prompt — the protocol handles tool discovery, parameter validation, and result framing. REST forces you to put the API surface into the agent’s prompt (or its function-calling schema), which costs tokens and means every release of the agent needs an updated tool definition. For agents that already speak MCP — Claude Code, Cursor, Claude Desktop, VS Code, Windsurf — MCP is strictly less work.

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What can each surface do?

Both surfaces now cover the full brand-owner product-entry workflow — an agent holding an MCP connection with a products:write/dashboard:write scoped token can create a product and enter every field a human could enter through the dashboard UI, without switching to REST. See MCP Tool Reference for the complete write-tool list. Webhooks and true bulk operations (multi-hundred-row imports) remain REST-only — those aren’t a good fit for a single LLM tool call.

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How do auth and rate limits compare?

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Can I use both?

Yes — and many integrations do. A common pattern:

• MCP server for the agent’s read path (lookup, search, resolve).
• REST API for the backend that owns mutations (catalog edits, webhook subscriptions, bulk imports) where you don’t want LLM-induced side effects.

Auth is independent — the OAuth tokens minted for the MCP write tool and the API keys minted for the REST API live in different namespaces and have different scopes.

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Where do I go next?