The Horizon MCP server exposes 26 tools and 2 context resources via the Model Context Protocol . Any MCP-compatible client can connect and trade prediction markets, equities, options, and crypto through natural language.
Tools are organized into 14 individual tools for common trading operations and 12 compound tools (including equity for stocks/options data) that group related capabilities via an action parameter. This keeps the tool list small enough for LLMs to load efficiently while preserving all 241+ capabilities.
Installation pip install horizon-sdk[mcp] # or uv pip install horizon-sdk[mcp]
This installs the mcp package alongside Horizon. The server is available as both a module and a console script:
Module
Console script
HTTP transport
Architecture The server lazily initializes a singleton Engine on the first tool call. Configuration comes from environment variables - no config files needed.
The MCP server (horizon.mcp_server) delegates to horizon.tools which manages a singleton Engine backed by the Rust core.
Most tools beyond the core 14 use an action-dispatch pattern:
{ "tool" : "wallet" , "params" : { "action" : "trades" , "params" : "{ \" address \" : \" 0x1234... \" , \" limit \" : 50}" } }
The action parameter selects the operation, and params is a JSON string with action-specific arguments. Each compound tool’s description lists all available actions.
Portfolio & Status engine_status Get the engine’s current state.
{ "running" : true , "kill_switch_active" : false , "kill_switch_reason" : null , "open_orders" : 3 , "active_positions" : 2 , "total_realized_pnl" : 12.45 , "total_unrealized_pnl" : -3.20 , "daily_pnl" : 9.25 , "uptime_secs" : 3600 }
list_positions Returns all open positions.
[ { "market_id" : "will-btc-hit-100k" , "side" : "yes" , "size" : 25.0 , "avg_entry_price" : 0.55 , "realized_pnl" : 0.0 , "unrealized_pnl" : 2.50 , "exchange" : "polymarket" } ]
list_open_orders Parameters: market_id (optional) - filter by market.
list_recent_fills Parameters: limit (default: 20) - number of fills to return.
portfolio_metrics Get portfolio metrics: total value, PnL, exposure, diversification, concentration. No parameters.
Trading submit_order Place a limit order on the engine’s configured exchange.
Parameter Type Description market_idstring Market identifier sidestring "buy" or "sell"pricefloat Probability price (0-1) sizefloat Number of contracts market_sidestring "yes" or "no" (default: "yes")
Returns the order ID on success, or {"error": "..."} on failure.
cancel_order Parameters: order_id - the ID to cancel.
cancel_all_orders Cancels all open orders across all exchanges. Returns {"canceled_count": N}.
Risk Management activate_kill_switch Parameters: reason - why you’re activating it.
This is an emergency stop. It immediately cancels all open orders across all exchanges. Use only in emergencies.
Market Data get_feed_snapshot Parameters: name - feed name (as configured in the engine).
{ "name" : "btc" , "price" : 97234.50 , "bid" : 97230.00 , "ask" : 97239.00 , "volume_24h" : 1234567.89 , "source" : "binance_ws" , "timestamp" : 1708185600.123 }
Discovery discover_markets Search for markets on an exchange.
Parameter Type Default Description exchangestring "polymarket""polymarket", "kalshi", "limitless", "alpaca", or "ibkr"querystring ""Search text limitint 10Max results market_typestring "all""all", "binary", or "multi"
get_market_detail Get detailed information for a specific market including price history, orderbook, recent trades, and top holders.
Parameter Type Default Description slug_or_idstring required Market slug or condition ID exchangestring "polymarket""polymarket" or "kalshi"
top_markets Get the highest-volume active markets.
Parameter Type Default Description exchangestring "polymarket""polymarket" or "kalshi"limitint 10Max results categorystring ""Category filter
Sizing kelly_sizing Compute Kelly-optimal position size.
Parameter Type Default Description probfloat - Your estimated probability (0–1) pricefloat - Current market price (0–1) bankrollfloat 1000.0Total capital fractionfloat 0.25Kelly fraction (0.25 = quarter Kelly) max_sizefloat 100.0Hard cap on position size
feed Feed management and data. 7 actions: list_feeds, start, metrics, all_metrics, health, parity, discover_events.
// Start a Chainlink feed { "action" : "start" , "params" : "{ \" name \" : \" eth_usd \" , \" feed_type \" : \" chainlink \" , \" config_json \" : \" { \\\" contract_address \\\" : \\\" 0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419 \\\" , \\\" rpc_url \\\" : \\\" https://eth.llamarpc.com \\\" } \" }" } // Check feed health { "action" : "health" , "params" : "{ \" stale_threshold \" : 30.0}" } // Check YES/NO price parity { "action" : "parity" , "params" : "{ \" market_id \" : \" will-btc-hit-100k \" }" }
order_management Advanced order operations. 5 actions: cancel_market, add_stop_loss, add_take_profit, list_contingent, deactivate_kill_switch.
// Add a stop-loss { "action" : "add_stop_loss" , "params" : "{ \" market_id \" : \" will-btc-hit-100k \" , \" side \" : \" yes \" , \" order_side \" : \" sell \" , \" size \" : 200, \" trigger \" : 0.40}" } // List all contingent orders { "action" : "list_contingent" , "params" : "{}" }
wallet Polymarket wallet analytics (public, no auth). 11 actions: trades, market_trades, positions, value, profile, top_holders, market_flow, profile_wallet [PRO], track [ULTRA], consensus [ULTRA], scan_signals [ULTRA].
// Get wallet positions { "action" : "positions" , "params" : "{ \" address \" : \" 0x1234... \" , \" sort_by \" : \" CURRENT \" }" } // Analyze trade flow for a market { "action" : "market_flow" , "params" : "{ \" condition_id \" : \" 0xabc... \" , \" trade_limit \" : 500}" }
analytics Quantitative analytics toolkit. 84 actions across categories: statistics, signals, portfolio, AFML (bars/labels/frac_diff), microstructure, state estimation, causality, execution, copula, portfolio optimization, hedging, pricing, bootstrap, risk/regime, and more.
// Compute Hurst exponent { "action" : "hurst_exponent" , "params" : "{ \" prices \" : [100, 101, 99, 102, 98]}" } // Kelly sizing adjusted for risk-free rate { "action" : "yield_adjusted_kelly" , "params" : "{ \" prob \" : 0.72, \" price \" : 0.58, \" rfr \" : 0.05, \" duration_days \" : 30}" } // Bootstrap Sharpe ratio confidence interval { "action" : "bootstrap_sharpe" , "params" : "{ \" returns \" : [0.01, -0.02, 0.03, 0.01, -0.01]}" } // Hedge analysis { "action" : "hedge_analysis" , "params" : "{ \" spot_prices \" : [100, 101, 99], \" hedge_prices \" : [50, 50.5, 49.5]}" }
See the tool description for the full list of 84 actions and their parameters.
scanning Market scanning, signals, and execution. 11 actions: sentinel_report [ULTRA], oracle_forecast [ULTRA], oracle_edges [ULTRA], whale_galaxy [ULTRA], llm_forecast, llm_scan, analyze_resolution, sniper_scan, execute_arbitrage, stealth_estimate [ULTRA], stealth_execute [ULTRA].
// Scan for LLM-detected edges { "action" : "llm_scan" , "params" : "{ \" min_edge_bps \" : 200, \" max_markets \" : 20}" } // Cross-exchange arbitrage { "action" : "execute_arbitrage" , "params" : "{ \" market_id \" : \" will-btc-hit-100k \" , \" buy_exchange \" : \" kalshi \" , \" sell_exchange \" : \" polymarket \" , \" buy_price \" : 0.48, \" sell_price \" : 0.52, \" size \" : 10}" }
unusual_whales Unusual Whales market intelligence. 36 actions across: flow (options_flow, stock_flow, dark_pool, market_tide, spike), Congress/insider (congress_trades, congress_trader, insider_trades), stock data (stock_info, stock_state, earnings, earnings_schedule, seasonality), options analytics (greek_exposure, greek_exposure_by_strike, greek_exposure_by_expiry, iv_rank, vol_term_structure, max_pain, option_chains), short interest (short_interest, short_volume, ftd), screeners (screener_stocks, screener_options), ETF (etf_holdings, etf_flow), institutions (institutions, institution_holdings, institution_ownership), calendars (economic_calendar, fda_calendar), other (news, prediction_whales, prediction_unusual, crypto_whales).
// Get unusual options flow for AAPL { "action" : "options_flow" , "params" : "{ \" ticker \" : \" AAPL \" , \" min_premium \" : 100000, \" is_sweep \" : true}" } // Get Congress trades { "action" : "congress_trades" , "params" : "{ \" limit \" : 50}" }
market_data Market data from Massive (Polygon.io). 24 actions across: price data (aggregates, snapshot, last_trade, last_quote, previous_close, grouped_daily), movers (gainers_losers, crypto_gainers_losers), reference (ticker_details, search_tickers, market_status, market_holidays), technical indicators (sma, ema, rsi, macd), options (options_chain, options_contracts), other (news, dividends, splits, crypto_snapshot, forex_conversion, forex_snapshot).
// Get OHLCV bars { "action" : "aggregates" , "params" : "{ \" ticker \" : \" AAPL \" , \" from_date \" : \" 2025-01-01 \" , \" to_date \" : \" 2025-03-01 \" , \" timespan \" : \" day \" }" } // Get real-time snapshot { "action" : "snapshot" , "params" : "{ \" ticker \" : \" AAPL \" }" }
cloud Horizon Cloud deployment and management. 12 actions: list_strategies, get_strategy, create_strategy, validate, list_credentials, save_credentials, deploy, stop, status, metrics, logs, account.
// Create a strategy { "action" : "create_strategy" , "params" : "{ \" name \" : \" Simple MM \" , \" code \" : \" import horizon as hz \\ n... \" }" } // Deploy { "action" : "deploy" , "params" : "{ \" strategy_id \" : \" uuid \" , \" credential_id \" : \" uuid \" , \" mode \" : \" paper \" }" } // Get metrics { "action" : "metrics" , "params" : "{ \" strategy_id \" : \" uuid \" }" }
marketplace Horizon strategy marketplace. 18 actions across: browse (browse, get_listing, leaderboard), publish (publish, my_listings, listing_earnings), subscribe (subscribe, unsubscribe, my_subscriptions, signals), purchase (purchase, my_purchases), payments (connect_payments, payment_status), verification (verify_performance, listing_badges, verify_trader, verification_status).
// Browse strategies { "action" : "browse" , "params" : "{ \" sort_by \" : \" sharpe \" , \" limit \" : 20}" } // Subscribe to signals { "action" : "subscribe" , "params" : "{ \" listing_id \" : \" uuid \" , \" size_scale \" : 0.5}" }
fund Multi-strategy fund management (requires HORIZON_FUND_MODE=1). 16 actions across: status (status, report, risk_dashboard, stress_test), strategies (deploy_strategy, stop_strategy, pause_strategy, resume_strategy, list_strategies, scale_strategy), analytics (nav_history, pnl_attribution, correlation_matrix, execution_report), memory (memory_query, memory_record).
// Deploy a strategy to the fund { "action" : "deploy_strategy" , "params" : "{ \" name \" : \" momentum \" , \" markets \" : [ \" will-btc-hit-100k \" ], \" mode \" : \" paper \" }" } // Get risk dashboard { "action" : "risk_dashboard" , "params" : "{}" }
account Horizon account and credentials. 3 actions: setup, login, key_status.
// Check key status { "action" : "key_status" , "params" : "{}" }
equity Equity and options market data. 6 actions: quote, search, options_chain, greeks, iv_surface, screener.
Uses Unusual Whales as the data source.
// Stock quote { "action" : "quote" , "params" : "{ \" symbol \" : \" AAPL \" }" } // Options chain { "action" : "options_chain" , "params" : "{ \" symbol \" : \" SPY \" }" } // Greek exposure { "action" : "greeks" , "params" : "{ \" symbol \" : \" TSLA \" }" } // IV term structure { "action" : "iv_surface" , "params" : "{ \" symbol \" : \" AAPL \" }" } // Stock screener { "action" : "screener" , "params" : "{}" }
Resources The server exposes two MCP resources for context injection:
URI Description horizon://statusEngine status as JSON horizon://positionsCurrent positions as JSON
Clients can attach these as context when starting a conversation.
Error Handling Every tool returns {"error": "..."} on failure instead of crashing the server. Common errors:
Error Cause "risk rejection: ..."Order blocked by risk pipeline "order not found: ..."Invalid order ID for cancel "feed not found: ..."Unknown feed name "unknown exchange: ..."Invalid exchange in discover "Unknown action '...'"Invalid action for compound tool "Invalid params JSON: ..."Malformed params string
Testing Verify the server starts and responds to the MCP initialize handshake:
echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' | python -m horizon.mcp
You should see a JSON-RPC response with the server’s capabilities and 26 tools. 
