Sergei's picture shows a menu located in the InterSystems View. The ISC logo for that view appears on the left of VS Code once you have a ObjectScript connection. You can configure Export settings, to an extent, as {objectscript.export: {}} in workspace or user settings.

See the README on the repository:

And a few more learning materials:

You are getting an"invalid JSON" error because the JSON you're POSTing is itself the OpenAPI 2.0 JSON Schema File. It defines how the standard works in JSON.

Instead, you'll need to post an OpenAPI document, abiding by those standards, defining your RESTful service.
More info here: