MCP Server

The Arbiter MCP server gives AI assistants direct access to live prediction market data. Ask your AI about market prices, trades, whale activity, and more — it calls the Arbiter API for you. 20 tools covering markets, trades, candles, orderbooks, events, wallets, whales, and cross-platform matching.

Quick Start

1. Install the package:

npm install @arbiterapi/mcp

2. Find the installed path:

node -e "console.log(require.resolve('@arbiterapi/mcp'))"

This prints the absolute path (e.g. /Users/you/project/node_modules/@arbiterapi/mcp/build/index.js). Use this path in the config below. 3. Get your API key at arbiterapi.com/signup. 4. Configure your AI assistant (see below).

Configuration

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"
      }
    }
  }
}

Replace /absolute/path/to/ with the actual path from step 2.

Claude Code

Add to .mcp.json in your project root (after running npm install @arbiterapi/mcp in that project):

{
  "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:

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

Available Tools

Markets

Tool	Description
`list-markets`	List markets across Polymarket and Kalshi, sorted by volume
`get-market`	Get a single market by ID
`search-markets`	Full-text search across market questions
`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

Events & Cross-Platform

Tool	Description
`list-events`	Events (grouped markets)
`get-event`	Single event with child markets
`matching-markets`	Find the same event on both Polymarket and Kalshi
`sports-markets`	Markets by sport and date

Wallets

Tool	Description
`get-wallet`	Wallet profile and trading metrics
`get-wallet-trades`	Wallet trade history
`get-wallet-pnl`	Realized and unrealized PnL
`get-wallet-positions`	Current open positions

Whales

Tool	Description
`get-whale-trades`	Large trades across all markets
`get-whale-stats`	Whale activity summary — count, volume, top markets

Platform Native

Tool	Description
`polymarket-markets`	Polymarket data with conditionId, clobTokenIds, outcomePrices
`kalshi-markets`	Kalshi data with event_ticker, yes_bid_dollars, volume_fp
`platform-stats`	Trade counts, markets covered, data range

Example Prompts

Once configured, try asking your AI assistant:

“What are the top prediction markets right now?”
“Show me whale trades in the last 24 hours”
“How much whale volume was there today?”
“List events on Polymarket”
“Get the orderbook for this market: poly_0x…”
“What are the current NBA sports markets?”

Getting Started

Core Concepts

SDKs

API Reference

Polymarket

Kalshi

Markets

Market Data

Events

Cross-Platform

Sports

Wallets

Whales

Webhooks

WebSocket

Auth & Keys

MCP Server

MCP Server

Quick Start

Configuration

Claude Desktop

Claude Code

Cursor

Available Tools

Markets

Events & Cross-Platform

Wallets

Whales

Platform Native

Example Prompts

​MCP Server

​Quick Start

​Configuration

​Claude Desktop

​Claude Code

​Cursor

​Available Tools

​Markets

​Events & Cross-Platform

​Wallets

​Whales

​Platform Native

​Example Prompts

MCP Server

Quick Start

Configuration

Claude Desktop

Claude Code

Cursor

Available Tools

Markets

Events & Cross-Platform

Wallets

Whales

Platform Native

Example Prompts