Claude Code

Add Horizon to Claude Code and trade prediction markets, equities, and options from your terminal.

Claude Code is Anthropic’s CLI for agentic coding. Adding Horizon as an MCP server gives Claude direct access to your trading engine - check positions, place orders, search markets, and manage risk through natural language.

Setup

1. Install Horizon with MCP support

   pip install horizon-sdk[mcp]
   # or
   uv pip install horizon-sdk[mcp]
   
2. Set environment variables

   export HORIZON_API_KEY="your-key"
   
   # For paper trading (default), no other vars needed.
   # For live Polymarket:
   export HORIZON_EXCHANGE="polymarket"
   export POLYMARKET_API_KEY="..."
   export POLYMARKET_API_SECRET="..."
   export POLYMARKET_API_PASSPHRASE="..."
   export POLYMARKET_PRIVATE_KEY="0x..."
   
3. Register the MCP server

   claude mcp add --transport stdio horizon -- python -m horizon.mcp
   

   This tells Claude Code to launch the Horizon MCP server as a subprocess using stdio transport.

4. Verify

   claude mcp list
   

   You should see horizon in the list of registered servers.

Usage

Once registered, just talk to Claude naturally. It will automatically use the Horizon tools when relevant.

Check your portfolio

> What's my current PnL and positions?

Claude calls engine_status and list_positions, then summarizes:

Your engine has been running for 45 minutes:
- Realized PnL: +$12.45
- Unrealized PnL: -$3.20
- Daily PnL: +$9.25
- 2 open positions, 3 open orders

Positions:
1. will-btc-hit-100k: 25 YES @ 0.55 (unrealized +$2.50)
2. fed-rate-cut-march: 10 NO @ 0.35 (unrealized -$0.70)

Search for markets

> Find bitcoin prediction markets on Polymarket

Claude calls discover_markets(exchange="polymarket", query="bitcoin"):

Found 5 BTC markets on Polymarket:
1. "Will BTC hit $100k by end of 2025?" - active, slug: will-btc-hit-100k
2. "Will BTC hit $150k by end of 2025?" - active, slug: will-btc-hit-150k
...

Size a trade with Kelly

> I think there's a 65% chance BTC hits 100k. The market is at 50 cents.
> How much should I buy with a $2000 bankroll?

Claude calls kelly_sizing(prob=0.65, price=0.50, bankroll=2000.0):

Kelly analysis:
- Edge: +15 cents (your 65% vs market's 50%)
- Quarter Kelly optimal size: 150 contracts
- Full Kelly would be 600, but quarter Kelly is safer

Want me to submit a buy order for 150 contracts at 0.50?

Place an order

> Yes, buy 150 contracts of will-btc-hit-100k at 0.50

Claude calls submit_order(market_id="will-btc-hit-100k", side="buy", price=0.50, size=150.0):

Order submitted:
- Order ID: p1
- Market: will-btc-hit-100k
- Side: buy
- Price: 0.50
- Size: 150 contracts

Emergency stop

> Kill switch NOW

Claude calls activate_kill_switch(reason="user requested emergency stop"):

Kill switch activated. All orders have been canceled.
Reason: user requested emergency stop

To resume trading, say "deactivate kill switch".

Tips

• Paper mode by default: If you don’t set HORIZON_EXCHANGE, the engine runs in paper mode. Safe for experimentation.
• Persistent engine: The MCP server maintains a singleton engine for the entire session. Positions and orders persist across tool calls.
• Multiple markets: You can work with multiple markets in the same session. The engine tracks positions independently per market.
• Context resources: Claude can read horizon://status and horizon://positions as background context for richer responses.

Removing

claude mcp remove horizon