Comparison
MCP vs OpenAPI: what to choose for agents
OpenAPI describes HTTP endpoints; MCP gives an agent tools in a standard protocol. Different layers — often used together.
In short
Not “either/or”: OpenAPI describes your HTTP API for developers and clients, MCP gives an AI agent ready-made tools in a standard protocol. MCP often wraps an existing API.
What each is
- OpenAPI — a REST API spec: endpoints, parameters, response schemas. For HTTP clients and SDK generation. Published/discovered via api-catalog.
- MCP — a protocol for connecting an agent to tools/data: tools with a JSON Schema, discovery via an MCP Server Card.
Side by side
| OpenAPI | MCP | |
|---|---|---|
| Describes | HTTP endpoints | Tools for an agent |
| Audience | Developer, HTTP client | MCP client, AI agent |
| Unit | Endpoint + parameters | Tool + JSON Schema |
| Discovery | /.well-known/api-catalog | MCP Server Card |
Key difference
OpenAPI is an HTTP-level API contract. MCP is a tool layer for the agent that hides transport details. An agent finds it easier to “call a tool” than to assemble an HTTP request from a spec.
Do both
Often yes: an MCP server wraps your OpenAPI API. Publish api-catalog for direct integrations and an MCP Server Card for agents.
How to verify
A scan checks for both api-catalog and an MCP Server Card — both discovery surfaces in one report.