MCP vs REST APIs

A REST API is an interface a developer integrates against by reading its docs; MCP is a standard that lets an agent discover and call tools and data uniformly, without a bespoke integration per source. MCP does not replace REST — an MCP server often wraps REST APIs — it standardises the agent-facing surface so one agent can use many tools the same way, which a pile of unrelated REST endpoints cannot offer on its own.

REST

Per-API interface, human integrator

MCP

Uniform agent-facing tool surface

Relationship

MCP often wraps REST

Adds

Discovery and uniformity for agents

Integration vs discovery

With REST, each new API is a new integration a developer writes. With MCP, an agent discovers the tools a server exposes and calls them through one interface, so adding a capability does not mean writing bespoke glue. The REST endpoints can still be underneath; MCP is the layer that makes them uniformly reachable by an agent.

Related standards

MCP

Questions

Should I replace my REST API with MCP?

No — expose it through MCP. The REST API remains; an MCP server wraps it so agents can discover and call it alongside your other tools uniformly.

Is MCP just OpenAPI for agents?

They overlap in describing interfaces, but MCP is designed around an agent discovering and invoking tools and context at runtime, not only documenting an API for a developer.