Responses with a large number of results should be paginated; the query parameters start and end can be used to specify how large a set of items to retrieve in each call, with a maximum page size of 500.
Additionally, for any call you can retrieve a count of the results (instead of the results themselves) by appending a query parameter of count=true.
So, to pull a large number of results, you start with a count:
Then, iterate over the list in blocks of 500:
Requests for page sizes larger than 500 will limited to start + 500.
Calls are rate-limited to prevent accidental overuse. If you exceed the limit you will receive a response of 403 Rate Limit Exceeded until enough time has elapsed between calls.