StockScreen MCP

A typed FastMCP server for Yahoo Finance-backed technical, fundamental, options, news, custom, and watchlist screening. It supports local stdio and containerized Streamable HTTP transports.

Tools

• run_stock_screen(screen_type, criteria, watchlist=None, save_result=None)
• get_stock_news(symbol, days_back=30)
• manage_watchlist(action, name, symbols=None)
• get_screening_result(name)

Legacy inputs and the five original screen categories are retained. Unknown criteria are rejected rather than silently ignored. Technical screens support the original price, volume, SMA-50/SMA-200, RSI, and ATR criteria. Fundamental screens include minimum/maximum market cap, P/E, dividend, revenue growth, profit margin, debt/equity, price/book, AUM, expense ratio, and volume. Options screens include IV, option volume, put/call ratio, spread, expiration-day, and earnings-day bounds. ETF, news, and nested custom criteria retain their original names. Explicit symbols or a watchlist are preferred. With neither, the server uses yfinance's documented screen query with size=250, US-region filters, category-aware EquityQuery/ETFQuery predicates, and assets/market-cap descending order. Universe metadata includes source, category, requested/returned size, sort, and as-of time. Missing requested metrics reject a symbol instead of becoming zero, and every rejected symbol retains reasons. Persistence names are restricted and normalized JSON writes are atomic under ~/.stockscreen; no migration runs during import.

uv sync --locked
uv run python stockscreen.py

The server uses stdio and emits no logs or migration messages to stdout. Yahoo Finance is an unofficial personal-use source and may be delayed, incomplete, rate-limited, or structurally changed. Results are not investment advice or guaranteed real-time data.

Docker / Streamable HTTP

The container runs as an unprivileged user, installs the locked production dependencies, and serves MCP at http://127.0.0.1:8000/mcp. Start it with:

docker compose up --build -d
Invoke-RestMethod http://127.0.0.1:8000/health

Connect a Streamable HTTP-capable MCP client to http://127.0.0.1:8000/mcp. The named stockscreen-data volume persists watchlists and saved results across container replacement. To avoid a port collision when running multiple servers, set MCP_HOST_PORT before starting Compose, for example $env:MCP_HOST_PORT=8002. Stop the container with docker compose down; add --volumes only when you intentionally want to delete the persisted data.

The Compose mapping intentionally binds to localhost. The endpoint has no authentication or TLS and must not be exposed to an untrusted network without a properly configured reverse proxy and access control.

Binding to loopback alone does not make the endpoint private: a browser can still reach it through DNS rebinding, so the server validates Host and Origin headers before a request reaches an MCP session. Requests carrying a foreign Host are answered with 421 Misdirected Request and those carrying a foreign Origin with 403 Forbidden, while same-origin loopback traffic and non-browser clients that send no Origin are unaffected.

Variable	Default	Purpose
MCP_TRANSPORT	stdio	stdio, http, or streamable-http.
MCP_HOST	127.0.0.1	Interface the HTTP server binds.
MCP_PORT	8000	Port inside the container.
MCP_PATH	/mcp	Streamable HTTP endpoint path.
MCP_HOST_PORT	8000	Host port Compose publishes on 127.0.0.1.
MCP_HOST_ORIGIN_PROTECTION	true	true, auto, or false. Disable only behind a proxy that performs the same validation.
MCP_ALLOWED_HOSTS	unset	Comma-separated extra hostnames permitted in Host.
MCP_ALLOWED_ORIGINS	unset	Comma-separated extra browser origins permitted in Origin.

Put the reverse-proxy hostname in MCP_ALLOWED_HOSTS when fronting the container, otherwise the guard rejects the proxied Host. Running uv run python stockscreen.py remains the stdio-compatible default outside Docker.

Run validation with uv lock --check, uv run ruff check ., uv run mypy ., uv run pytest, uv build, and uv run python scripts/verify_wheel.py. CI also builds the container and performs health plus MCP tool-discovery checks over Streamable HTTP. Domain/provider/persistence branch coverage is gated at 90%. Set YFINANCE_LIVE=1 to opt into live shape smoke tests.