Claude Desktop

Add Horizon to Claude Desktop for conversational trading across prediction markets, equities, and options.

Claude Desktop supports MCP servers natively. Add Horizon to trade prediction markets, equities, and options, check positions, and analyze markets through conversation.

Setup

1. Install Horizon

   pip install horizon-sdk[mcp]
   # or
   uv pip install horizon-sdk[mcp]
   
2. Find your Python path

   The Claude Desktop config needs the full path to your Python interpreter:

   which python
   # e.g., /Users/you/.pyenv/shims/python
   # or:   /opt/miniconda3/bin/python
   
3. Edit Claude Desktop config

   Open Claude Desktop settings and navigate to the MCP configuration file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json

   Add the Horizon server:

   {
     "mcpServers": {
       "horizon": {
         "command": "/full/path/to/python",
         "args": ["-m", "horizon.mcp"],
         "env": {
           "HORIZON_API_KEY": "your-key",
           "HORIZON_EXCHANGE": "paper"
         }
       }
     }
   }
   

   Replace /full/path/to/python with the output of which python. Claude Desktop does not inherit your shell’s PATH, so the full path is required.

4. Restart Claude Desktop

   Quit and reopen Claude Desktop. You should see a hammer icon indicating MCP tools are available.

Conversation Examples

Morning portfolio check

You: How are my positions doing?

Claude: Let me check your trading engine.

Your engine has been running for 2 hours:
- Daily PnL: +$15.30
- 3 open positions:
  1. will-btc-hit-100k: 50 YES @ 0.52 → unrealized +$4.00
  2. fed-rate-cut-march: 20 NO @ 0.40 → unrealized +$1.20
  3. eth-above-5k: 15 YES @ 0.30 → unrealized -$0.90

No kill switch active. 5 open orders working.

Research and trade

You: Find me prediction markets about the Fed on Kalshi

Claude: [calls discover_markets]

Found 4 Fed-related markets on Kalshi:
1. KXFED-26MAR19 - "Fed rate cut in March 2026?" (active)
2. KXFED-26APR30 - "Fed rate cut by April 2026?" (active)
3. KXFED-26JUN18 - "Fed rate cut by June 2026?" (active)
4. KXFED-26TOTAL - "Total Fed cuts in 2026" (active)

Would you like to analyze any of these?

You: I think there's a 70% chance the Fed cuts in March. The market is at 55 cents.
    What's my optimal size with a $5000 bankroll?

Claude: [calls kelly_sizing]

Kelly analysis for your Fed March cut thesis:
- Your edge: +15 cents (70% vs 55%)
- Quarter Kelly size: 340 contracts at $0.55
- Expected edge per contract: $0.15
- Recommended: start with 100 contracts to test the thesis

Want me to place a buy order?

For Live Trading

Update the env variables in the config to switch to a live exchange:

{
  "mcpServers": {
    "horizon": {
      "command": "/full/path/to/python",
      "args": ["-m", "horizon.mcp"],
      "env": {
        "HORIZON_API_KEY": "your-key",
        "HORIZON_EXCHANGE": "polymarket",
        "POLYMARKET_API_KEY": "...",
        "POLYMARKET_API_SECRET": "...",
        "POLYMARKET_API_PASSPHRASE": "...",
        "POLYMARKET_PRIVATE_KEY": "0x..."
      }
    }
  }
}

Always test with HORIZON_EXCHANGE=paper first. Live trading submits real orders with real money.

Troubleshooting

Issue	Fix
No hammer icon	Check that the Python path is absolute and correct
”Module not found”	Ensure horizon-sdk[mcp] is installed in the Python environment at that path
Tools not appearing	Restart Claude Desktop after editing config
Connection timeout	Check HORIZON_API_KEY is set and valid