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REST, SDK and MCP: where each interface belongs

A practical distinction between a core HTTP API, developer SDKs and MCP as an optional tool-facing integration layer.

Updated 2026-09-26 · SlateMoth

REST as the core contract

A well-defined HTTP API is a broadly interoperable foundation. It can be called by applications, agents, command-line tools and SDKs.

SDKs reduce integration friction

Node and Python SDKs can provide typed requests, retries, streaming helpers and ergonomic abstractions while preserving the underlying API contract.

MCP serves a different entry point

MCP can expose selected capabilities as tools or resources to compatible agent hosts. It does not need to become the internal transport for every service.

Keep one source of truth

REST, SDK and MCP entry points should converge on the same core authorization, policy and execution services.

Choosing an interface

Use HTTP for broad interoperability, an SDK for developer ergonomics, and MCP when a compatible agent environment benefits from tool discovery.