Arena Predictions (arena-predictions.com): install arena-prediction-cli with `npm install -g arena-prediction-cli`, then run `arena login` once.
Arena Basic costs $9.99 a month or $49.99 a year. There is no free tier.
Limits: paper money only; only the markets Arena lists; no orders are sent to any exchange; a fill is at the best displayed price for the whole size, with no fee charged; API keys are read-only; and the text-to-ticker resolver covers NFL games only for now.
Paste everything below into your agent.

You have the Arena CLI installed as `arena`. It is Arena Predictions, paper
trading for prediction markets at live prices, virtual money only, so nothing
you do can spend real funds.

Start by running `arena` on its own. It prints my balance, how many positions I
have open and the current season, so you do not need a discovery round trip.

The commands you will want:
  arena markets --league nba          open markets
  arena search "kansas city"          find a market by text (titles name cities)
  arena resolve "chiefs ml"           a bet in words to an instrument id, ticker and side
  arena game "chiefs dolphins"        every instrument on one game, with its ids
  arena instrument <ins_id>           one instrument: what YES means, which ticker holds it
  arena market <ticker|ins_id>        one market in detail
  arena orderbook <ticker|ins_id>     resting bids and asks
  arena chart <ref> --range 24h       the recent price path
  arena positions                     open positions with P&L
  arena balance                       spendable paper dollars and net worth
  arena buy <ticker|ins_id> --side yes --contracts 10 --limit 45 --yes
                                      buy at 45c or better; without --limit it buys at the ask
  arena orders                        my resting limit orders
  arena cancel <order-id> --yes       withdraw a resting order and free its hold
  arena sell <trade-id> --yes
  arena history                       settled trades
  arena stats                         this season graded: win rate, calibration, drawdown

Store instrument ids (ins_...), not tickers: an id is permanent. With an
instrument id, --side means the instrument's side, and the CLI maps it to the
ticker's side and shows both.

Your output is piped, so the CLI is already in agent mode: you get TOON instead
of tables and you are never prompted. buy, sell and cancel need --yes; without
it they exit 2 and send nothing. arena settle needs no --yes, because it only
settles trades whose markets have already resolved. Add --json to any command
if you would rather parse JSON.

Exit codes: 0 ok, 1 internal error (a bug, report it), 2 bad usage, 4 not
signed in, 5 needs an Arena Basic membership, 6 refused by the backend, final
except a 429 after Retry-After, 7 network or server error.

Before you buy anything, read the orderbook and tell me the ask and the stake.
arena buy ... --dry-run shows the price, the stake and the estimated venue fee,
which is not charged on paper. Before you sell, run arena market <ticker> and
tell me the side's bid (yes_bid or no_bid) and contracts x bid / 100 dollars. A
market sell's --dry-run shows no price. Never place or close a trade I did not
ask for.