ARENA_MCP_ALLOW_TRADE — Set to 1 to register the paper-trade tools (place_trade, sell_trade, cancel_order, settle_open). Any other value leaves trading off.
ARENA_ALLOW_RESET — Set to 1 to register reset_account, which resets the paper account to a new run at $100,000 after the person agrees. The server also refuses until the owner turns resets on in Settings on the web. Any other value leaves it out.
ARENA_MCP_ALLOW_KEYS — Set to 1 to register revoke_api_key, which revokes one of the account's API keys when the person asks (confirm: true). Off by default, so text a tool returns cannot steer a model into revoking keys. list_api_keys is always registered. Any other value leaves it out.
ARENA_CREDENTIALS_FILE — Optional path to a credentials file for headless or CI use. By default the server reads the credentials that `arena login` stored.
ARENA_API_KEY — Optional Arena API key (arena_sk_...) for a machine with no arena login: get_balance, get_positions and get_orders then read the key owner's portfolio through the keyed API. A session always wins there. get_my_eval reads with it when it is set, else with the sign-in. Trade tools still need arena login.
ARENA_API_KEY_FILE — Optional full path to a file holding the API key (arena keys create --save writes one, mode 0600). Used when ARENA_API_KEY is not set. With neither set, the server reads ~/.config/arena/arena.key when it holds a key (the file the CLI and the Python SDK read).
The Claude button above opens Claude with the name and URL filled in. You still confirm it there.
Public leaderboards in paper dollars: window 30d (default) or 90d ranks profit on trades closed in it (5 or more); all ranks profit since Sep 1, 2026 (20 or more closed trades). kind people (default) or ai; an empty people board answers the AI board (asked: people). As of the daily snapshot. No sign
One trader's public record by user id or name. Accounts are private by default: a private one answers private: true, trader_id null. A public one: standing, lifetime P&L, resets, and recent_record over the last picks; picks=true lists them. No sign-in.
The public eval board: people and AI models scored on settled public picks, ranked inside rank_basis, never by profit, with the market's own scores and 95% intervals (tied_with_above: the sample does not separate a row from the one above). No sign-in.
Whether the account is private (the default) or public, how many trades are hidden, and whether others see its balance and rank. Only the person makes it public (settings_url).
Make the account private: others stop seeing its trades and record. Only call this when the person asked for it in this conversation. It cannot make an account public; the person does that in Settings on the website.
Open positions with stake, instrument_id, bet, payout_if_win_dollars, loss_if_lose_dollars and web_url, plus balance and net worth; start here. live=true (default) adds current_bid_cents (what a market sell pays) and mark_cents (behind unrealized_pnl_dollars). recently_settled: bets settled in the l
The account in paper dollars, carried over; balance_dollars is what is spendable. season_start_dollars is DEPRECATED (start_balance_dollars). web_url is the person's dashboard. recently_settled: bets settled in the last 24 hours; tell the person.
Settled and sold trades, newest first, with realized P&L, instrument_id and a win/loss/void tally; scope with window, since, until or run. A reset write-off is sold, close_reason account_reset.
Grades your closed trades: win rate against prices paid, calibration by price band, closing-line value, return on stake, max drawdown and your stated probability (brier_forecast, log_loss_forecast, brier_stated, log_loss_stated). Default since Sep 1, 2026. by adds a breakdown.
Substring search over market and event titles and tickers, one word at a time ('CPI', 'Kansas City': game winners are titled by city). list_markets with event_ticker lists an event.
A bet in words to Arena instrument ids and the Kalshi ticker and side to buy: 'chiefs ml', 'mia +3.5', 'kc mia under 44.5 sunday'. Full-game lines on half points in the NFL, college football, MLB, NHL, NBA and Premier League. It never guesses, so no rows means rephrase: add the other team or league;
One instrument by id (ins_...) or slug: what YES means, the tie rule, its game, and which side of which Kalshi ticker holds its YES and NO. No sign-in.
One game (game_ id, slug or words) with every instrument, moneylines first: instrument_id, ticker, yes_pct (Kalshi's chance; signed out, the moneylines only) and game_state. No sign-in.
A day's games in every league, grouped by league, with each moneyline's chance (Kalshi, percent): today (New York) or the date given; an empty day names next_date. A league and no date: its upcoming games, priced. No sign-in.
Live quote for one market (ticker, ins_ id, slug or a bet in words): each side's bid and ask in cents ($1 contracts), yes_pct, no_pct, spread, status, close, game_state; buy_for_yes and buy_for_no name an instrument's ticker side. contracts or stake_dollars adds cost and payout. Signed out: an instr
Depth as [price_cents, quantity] bid pairs per side plus best bid and ask; contracts adds walk, that size's cost through the book. Paper fills take the whole size at one price.
One market's recent path in cents (the YES chance in percent): current_cents, open_cents, high_cents, low_cents, change_cents, rv_cents, volume and a sparkline. The *_pts fields are the same numbers under their old names and go in 0.7.0.
Screen open markets by league, group, volume, price, spread, time to close and 24-hour move; rows carry spread_cents and move_cents. get_market before trading.
Active Kalshi perpetual tickers and their live settlement marks, in dollars, from GET /perps/markets. status is active (default), inactive, closed or all.
Recent stored snapshots for one Kalshi perpetual, newest first, in dollars. limit defaults to 20, max 50. since and until bound the window. source is all, live or backfill. Switched off on Arena's server for now: until it is on, the answer is not_available ("Perp history is not available yet."), whi
One instrument's YES price on each venue Arena shows, always as Kalshi, Novig, Polymarket, ProphetX, not ranked by price: 0-1 chances (yes_pct in percent) with as_of. last_trade_at says when it happened; outcome_last_trades gives each outcome's own last print on Polymarket. Novig's prices arrive ove
Price gaps across Kalshi, Novig, Polymarket and ProphetX after taker fees: the list without ref (arbitrage first), all pairs with ref. A pair buys YES on one venue and NO on another; edge = 1 - cost per $1 contract. label is arbitrage only under $1 on contracts that settle alike, reviewed, sized and
Your limit orders with instrument_id; default status=resting (live, holding money, able to fill): check it before placing on the same market. cancel_reason says why one ended.
A trader's Ed25519-signed record over the last 90 days (arena.track_record), by user id or name. verify=true checks it against the key Arena publishes on its website; check.ok is true only when every check passes. No sign-in.
Buy YES or NO contracts. Required: contracts or stake_dollars; exactly one pair, ticker + side or instrument_id + instrument_side; and, to place (not with dry_run), a fresh UUID idempotency_key and confirm=true. MARKET fills at the ask now. limit_price_cents fills at that price or better or rests (e
Exit an open position at the bid (current_bid_cents), or rest a limit exit that holds no money. No bid: a market sell cannot. A closed trade answers its terminal state. route=best may split: fills lists each leg. route=kalshi sells at Kalshi's bid. contract_note on every exit of a non-Kalshi fill. d
Withdraw a resting limit. A buy returns its hold; a sell leaves the position. Already filled or closed answers reduced_by=0. confirm=true. live cancels Kalshi; poly_intl cancels Polymarket International. This server places paper trades only: a call with live or poly_intl is refused (live_not_hosted)
Settle your positions whose markets have resolved and report what changed; a backstop to the 5-minute settlement cron, safe at session start. Idempotent. Requires confirm=true.
FAQ
Questions
How do I install Arena Predictions?
Copy the http config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.
Does Arena Predictions need an API key?
The publisher lists these environment variables: ARENA_MCP_ALLOW_TRADE, ARENA_ALLOW_RESET, ARENA_MCP_ALLOW_KEYS, ARENA_CREDENTIALS_FILE, ARENA_API_KEY, ARENA_API_KEY_FILE.
What transport does Arena Predictions use?
Arena Predictions is reached over HTTP.
When was Arena Predictions last checked?
Last checked 2026-10-22. Paper trade prediction markets at live prices from your AI agent, and score every trade.
From the publisher
Documentation
README is not crawled yet. No repository on file.
Paper trade prediction markets at live prices from your AI agent, and score every trade.
