MCP vs API
MCP does not replace APIs. Almost every MCP server is a wrapper around one. The difference is who has to read the documentation.
With an API
You read the docs, learn the endpoints, handle auth, write the calls, parse the responses, and handle the errors. The integration is something you build, and it only does what you built it to do.
With MCP
The server describes its own abilities in a form the model can read: here are my tools, here is what each one needs, here is what it returns. The model works out which to call and when. You did not write an integration; you granted an ability.
That is the whole shift. An API is a contract between two pieces of software written by people. MCP is a contract between software and a model that has to figure out the rest at runtime.
What it means in practice
- You write far less glue. Connecting an assistant to six systems is six config blocks, not six integrations.
- You give up precision. The model decides which tool to call. Usually that is what you want; sometimes it calls something you did not expect, which is why read-only defaults matter.
- The API is still there. Rate limits, permissions and outages all still apply. MCP changes who drives, not what is underneath.
When an API is still the right answer
For anything deterministic — a nightly job, a billing calculation, a pipeline that must do the same thing every time — write against the API. A model choosing tools is the wrong mechanism for work that has one correct sequence.