NegativeEV MCP server

Grade any MLB, WNBA, PGA or ATP bet against thousands of play-by-play game simulations, from inside your AI client.

Whether a bet is worth taking depends on tonight's lineups, today's injuries, and the weather at first pitch. None of that is in a model's weights. Asked cold, a model answers fluently and wrongly. This server returns a probability counted from simulations of the actual game: each leg's simulated win probability, the probability the sportsbook's price implies, and the edge between them.

This is a hosted remote server. There is nothing to build or run from this repo. The repo is the server's public face and carries a mirror of its registry record (server.json).

Connect

No API key, no signup. Anonymous calls work immediately. The server speaks plain Streamable HTTP, so any MCP client can connect to https://negativeev.com/mcp.

Claude Code

claude mcp add --transport http negativeev https://negativeev.com/mcp

Claude Desktop and claude.ai

Settings → Connectors → Add custom connector, then paste https://negativeev.com/mcp as the URL.

Cursor

Add {"negativeev": {"url": "https://negativeev.com/mcp"}} under mcpServers in ~/.cursor/mcp.json. Also listed on cursor.directory.

VS Code (Copilot)

code --add-mcp '{"name":"negativeev","type":"http","url":"https://negativeev.com/mcp"}'

ChatGPT

Settings → Security and login → enable Developer mode, then add https://negativeev.com/mcp as a connector at chatgpt.com/plugins. Developer mode is required for custom MCP connectors and is available on Pro, Plus, Business, Enterprise and Education accounts on the web.

There is also a Claude Code plugin that wraps this server: jessejohnsohn/negativeev-bet-checker. Install with claude plugin install negativeev-bet-checker.

Opening https://negativeev.com/mcp in a browser shows the same install steps.

Tools

Tool	What it does
check_bet	Grades a bet written as plain text, including a multi-leg parlay in one string. Returns each leg's simulated probability, the implied probability from the price, and the edge. It prices a bet you name. It does not search the board for value.
get_slate	Says whether there is a checkable slate right now. Free. Spends no check.
get_usage	Reports checks remaining and when the next frees up. Free. Spends no check.

Call get_slate first to confirm there is a checkable slate. check_bet spends one of the caller's checks only when the bet fully grades, and every result says so outright in its status and check_spent fields. A bet that comes back ungraded was understood. It is simply not on the simulated slate, so re-sending it with different wording returns the same answer. Check get_slate instead.

Limits and auth

Anonymous calls share a per-device quota of 100 checks a day, on its own counter. Signing in makes checks unlimited, with a pace cap of 1000 checks an hour. Send a signed-in user's access token as Authorization: Bearer. Details at negativeev.com/auth.md. An invalid or expired token is rejected with a 401 rather than silently downgraded, so re-authenticate rather than retrying anonymously.

Details

Endpoint	https://negativeev.com/mcp
Transport	Streamable HTTP (stateless)
Sports	MLB, WNBA, PGA, ATP
Registry name	com.negativeev/bet-checker
Auth	Optional bearer token, details at negativeev.com/auth.md
Server card	/.well-known/mcp/server-card.json
Cost	Free

NegativeEV checks bets. It takes no bets and sells no picks.