Billy API

Billy reads Polymarket and Kalshi against the sportsbook line for MLB, the NFL and college football, pre-game, on moneyline, spread and total. The Billy API gives any AI agent the same read the app shows, as a remote MCP server. It is read-only and free.

Endpoint: https://mcp.billybets.ai (MCP Streamable HTTP, stateless, JSON responses). Every answer comes from the same precomputed snapshots the app renders from, refreshed about every five minutes.

game takes a Billy game id, or a team (code or name) with an optional opponent and sport. It returns the signals that fired on the game with the reason on today’s prices, the Alpha read when three or more signals agree on one pick, the best allowed price and venue for each pick, and the live board when the game is in progress.

slate returns today’s games (US Eastern date), ranked the way Billy’s slate ranks them, in-progress games first and then by start time, with the top read per game. An optional sport filter narrows it to one league.

live returns every live fire across in-progress games. Live fires have not launched yet, so today it always answers with the empty state: “No live fires right now.”

Every response has a short plain-language summary an agent can repeat as written, plus the structured fields behind it: the game (teams, start time, status, a link to its Billy page), each signal with its market, pick and reason, each pick with its best allowed price (American odds, the same price in cents, and the venue name), and the Alpha read when there is one.

Every response carries two fixed fields. A client using the API must show both to the end user, unaltered. The plain-language summary ends with both lines, and they also arrive as their own content block annotated for the user (MCP audience: ["user"]).

Attribution: “Signals by Billy”, with the link in attribution.url (the game’s Billy page, or the slate).

Disclosure: “Billy makes this market. This is what the desk sees.” Billy is a market maker on the exchanges it reads. The disclosure is there so a reader always knows that.

The API returns information about prices. A price and a venue name are information. The API does not place bets, take payments, or hold funds, and it never returns a link to a sportsbook, a bet slip, a referral or affiliate parameter, or copy urging anyone to bet. The only links in a response point to Billy’s own pages. Billy takes no money from sportsbooks, and sportsbooks and their affiliates are not eligible to use the API.

The API never returns records: no hit rate, no win-loss record, no scorecard, and no count of how often a signal has fired. The reason on a signal is always a fact about today’s prices. The API never returns anything from Billy’s own trading desk: no quotes, fills, positions, or order flow.

Free. During the preview the endpoint may require a shared key, passed as Authorization: Bearer, an x-billy-key header, or a ?key= query parameter. Free per-developer keys are coming. Requests are limited to 600 calls per hour per client; past that the endpoint answers HTTP 429 with a Retry-After header.

Terms: show the attribution and disclosure unaltered; no resale; no redistribution as a feed; no removal of attribution. Billy may revoke access for any of these.

In Claude, open Settings, then Connectors, choose Add custom connector, name it Billy, and paste https://mcp.billybets.ai as the URL. Then ask about a game, for example “What is Billy seeing in Ohio State against Illinois?”

Questions or a directory review: billy@megalabs.xyz.