If you're the designer of the API in question, why did you design it to include these "extra params"? Maybe they are needed elsewhere, but in your new code you just need a subset of the returned data? We don't know.
JSON is a very dynamic format so even if you get a hundred extra fields it doesn't matter (except maybe for the additional time for parsing more data), as long as you get the ones you need.
I'll give you an example. Imagine that you're writing a small program to display the temperature outside. You have a thermometer that does not have any display but you're able to get a JSON response from it, in the following format:
You don't need the
canYouGoSkiing fields, but their presence will not cause your application to break.
With that information, I say ignore the extra fields. You may not need them, but probably other people do and the API has to accommodate their needs too, not only yours.