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

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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.

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Conversation Examples

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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.

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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?

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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.

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Troubleshooting

IssueFix
No hammer iconCheck 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 appearingRestart Claude Desktop after editing config
Connection timeoutCheck HORIZON_API_KEY is set and valid