We would simplify this by removing end_time, content_type and filters, rename preferred_interpretation to plain interpretation. Also interpretation kinda already does the filtering, end_time could be when post payout which means 7*24 hours from time of publish, so no need to over complicate the logic. Also this json should inside json_metadata, not entire json_metadata but part of it
json_metadata:{..... poll: {} }

{
  "version": "0.1",
  "question": "How many polls do you want to see per day?",
  "choices": ["Less than 1", 1, 2, "three", "4-ish", "V", "six", 7, "e8t", "nine", 10, "10+"],
  "interpretation": "tokens",
  "token": "HIVE:HP"
}

Also would be beneficial if UI sends token data at the time of casting. custom json id could be just poll, action is unnecessary. Also perhaps instead of poll id, use author/permlink as it is already part of unique post?!

{
  id: 'poll',
  json: {
    "author": "demo",
    "permlink: "test",
    "choice": 1
    "extras" : "200000 VESTS"
  }
}