@arbiterapi/mcp

MCP server for the Arbiter prediction market API. Gives AI assistants access to live prediction market data from Polymarket and Kalshi.

20 tools covering markets, trades, candles, orderbooks, events, wallets, whales, and cross-platform matching.

Setup

1. Install:

npm install @arbiterapi/mcp

2. Get your API key at arbiterapi.com/signup.

3. Configure your AI assistant:

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "arbiter": {
      "command": "node",
      "args": ["/absolute/path/to/node_modules/@arbiterapi/mcp/build/index.js"],
      "env": {
        "ARBITER_API_KEY": "your-api-key"
      }
    }
  }
}

Find the path with: node -e "console.log(require.resolve('@arbiterapi/mcp'))"

Claude Code

Add to .mcp.json in your project root:

{
  "mcpServers": {
    "arbiter": {
      "command": "node",
      "args": ["node_modules/@arbiterapi/mcp/build/index.js"],
      "env": {
        "ARBITER_API_KEY": "your-api-key"
      }
    }
  }
}

Cursor

Go to Settings > MCP Servers and add with the same command and args.

Tools

| Tool | Description | |------|-------------| | list-markets | List markets across Polymarket and Kalshi | | get-market | Get a single market by ID | | search-markets | Full-text search across markets | | get-price | Current or historical price for a market | | get-orderbook | Live orderbook (bids, asks, spread) | | get-trades | Trade history for a market | | get-candles | OHLCV candlestick data | | list-events | Events (grouped markets) | | get-event | Single event with child markets | | matching-markets | Cross-platform matches (Polymarket + Kalshi) | | sports-markets | Markets by sport and date | | get-wallet | Wallet profile and metrics | | get-wallet-trades | Wallet trade history | | get-wallet-pnl | Wallet PnL | | get-wallet-positions | Current positions | | get-whale-trades | Large trades across all markets | | get-whale-stats | Whale activity summary | | polymarket-markets | Native Polymarket data | | kalshi-markets | Native Kalshi data | | platform-stats | Platform statistics |