MCP server for the MarketMaster prediction-market data API. Pull live edges, arbitrage spreads, market snapshots, and the whale feed (Kalshi and Polymarket) straight into Claude or Cursor.

Two ways to use it

Hosted — nothing to install. Paste this URL into any MCP client that supports remote servers (Claude, Cursor, and anything else speaking streamable-http):

https://api.marketmaster.live/mcp

It authenticates with OAuth 2.1 (PKCE, dynamic client registration), so there is no key to paste and nothing to keep up to date.

This package — stdio, for clients that want a local process. Covered below.

Tools

mm_edges — mispriced edges, ranked
mm_markets — latest market snapshots
mm_market — one market + its edges
mm_arbitrage — cross-platform spreads
mm_whales — large real-money trades
mm_status — your tier, limits, usage

Setup

Get an API key at https://marketmaster.live/dashboard (looks like mmk_live_...).

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "marketmaster": {
      "command": "npx",
      "args": ["-y", "@marketmaster/mcp"],
      "env": { "MARKETMASTER_API_KEY": "mmk_live_your_key" }
    }
  }
}

Cursor

Add to ~/.cursor/mcp.json (same shape as above), then enable it in Settings → MCP.

Try it

"Use MarketMaster to find the 5 biggest Kalshi edges right now." "Any cross-platform arbitrage over 3%?" "Show recent whale trades over $25k."

Read-only — never places trades or touches funds. Full API docs: https://marketmaster.live/developers

First call, if you just want the data

The MCP server wraps a plain REST API. To check a key works before wiring anything up:

curl "https://api.marketmaster.live/v1/edges?limit=5" -H "x-api-key: mmk_live_your_key"

Note for Python: the stdlib urllib default user agent is blocked by the CDN in front of the API (you get a 403 HTML page, not JSON). requests, httpx and the official SDK all work, as does urllib with any custom User-Agent set.

What the numbers mean

edge_pct is gross. edge_after_fees is what survives venue fees, and the two routinely differ by more than the edge itself.
settlement_risk: "divergent" means the two venues resolve the same question on different dates. That is not arbitrage, however good the spread looks.
Live worked examples, recomputed daily: is there arbitrage between Kalshi and Polymarket? · how accurate are the prices?