Sleeper Draft Assistant MCP

A read-only prototype that gives ChatGPT a fresh, league-aware Sleeper draft snapshot while a pick clock is running.

The server exposes one focused Streamable HTTP MCP tool, get_live_draft_context. Every call refreshes the draft, picks, traded picks, league, rosters, and league users. It returns:

• the manager's drafted players, position counts, filled/open starter slots, and bench space;

• the current selection, manager on the clock, and picks until the user's next selection;

• league scoring, roster, and draft settings;

• the full draft history and compact positional summaries for every other roster;

• currently undrafted players by rostered position.

Sleeper player metadata is cached for 24 hours because /players/nfl is a large, slow-changing catalog. Availability is still calculated from freshly fetched picks on every call. The returned sleeper_search_rank is discovery metadata—not draft advice—and should be combined with a separate rankings or research source.

Run locally

Requirements: Node.js 22 or newer.

npm install
cp .env.example .env
npm run dev

Optionally set SLEEPER_USER_ID to a Sleeper username or user ID. If it is unset, the MCP call must provide user.

The endpoints are:

• POST /mcp — stateless Streamable HTTP MCP

• GET /health — process health

• GET / — service metadata

Related MCP server: sleeper-caffeine MCP

Verify the prototype

npm test
npm run test:integration
npm run typecheck
npm run build
npx @modelcontextprotocol/inspector@latest

Point MCP Inspector at http://localhost:3000/mcp, list the tools, and call get_live_draft_context with a real draft_id and user.

The included Dockerfile builds a production image for any HTTPS-capable container host:

docker build -t sleeper-mcp .
docker run --rm -p 3000:3000 -e SLEEPER_USER_ID=your-user sleeper-mcp

For ChatGPT, expose the endpoint through public HTTPS or a supported secure tunnel. Then enable Developer mode under Settings → Security and login, add an MCP server from ChatGPT Plugins, and enter the HTTPS URL including /mcp. Start a new chat, add the connection from the tools menu, and ask a draft question from the mobile app.

Keep the default localhost binding when using a secure tunnel. If you deliberately expose the server, set HOST=0.0.0.0, configure MCP_BEARER_TOKEN when the client can send a bearer credential, and place TLS at the hosting edge. Browser-originated requests are rejected unless their exact origins appear in MCP_ALLOWED_ORIGINS; server-to-server MCP requests normally omit Origin.

Prototype boundaries

• Read-only: there is no code path that makes a Sleeper selection or modifies a league.

• No ranking engine: external rankings, projections, injury research, and news remain separate.

• Snake/linear drafts: current and future pick math supports these formats, including traded picks. Auction nomination order is reported as unsupported.

• Public Sleeper data: the optional bearer token protects the endpoint, but it is not per-user authorization. Use a secure tunnel for the personal proof and add OAuth before operating this as a shared service.

• Availability depends on the Sleeper player catalog. Players without a finite positive search_rank are omitted from the compact candidate lists but remain visible in draft history when selected.

Environment variables

Source references

• Sleeper's API documentation describes its unauthenticated, read-only endpoints and usage limits.

• OpenAI's MCP server guide covers tool schemas, annotations, results, and the TypeScript SDK.

• OpenAI's connection guide covers public HTTPS or secure tunnels, MCP Inspector, Developer mode, and adding the /mcp endpoint to ChatGPT.