You still need to write a spec with protobufs. It's just that the spec is much more succinct and easy to read. And you can generate docs from it. E.g.: https:/

You still need to write a spec with protobufs. It's just that the spec is much more succinct and easy to read. And you can generate docs from it. E.g.: https://cloud.google.com/appengine/docs/admin-api/reference/rpc/google.cloud.location#listlocationsrequest https://cloud.google.com/appengine/docs/admin-api/reference/... Do an experiment, take a Protobuf spec for some Google API and convert it into OpenAPI.