Some endpoint descriptions aren't accurate or not very good explained.
For example: In all /v3/groups/{groupId} endpoints, the path parameter groupId can be a UUID of a Group or simply party for your current party group.

Since the official Habitica Api documentation does not contain reusable objects, but basically each request and each response has its own structure, I started writing the OpenAPI in the same way.
Then I tried to use the OpenAPI Generator to generate some client code from the specification.
Generator creates objects with random names out of anonymous json objects.
Therefore it's better to make it properly and make each object into it's own schema.