StockFlow MCP

A typed FastMCP server for stock metadata, price history, technical indicators, financial statements, calendars, and option chains through yfinance. It supports local stdio and containerized Streamable HTTP transports.

Tools

• get_stock_data_v2(symbol, include_financials=False, include_analysis=False, include_calendar=False)
• get_historical_data_v2(symbol, period, interval='1d', prepost=False)
• get_options_chain_v2(symbol, expiration_date=None, include_greeks=False)

Historical downloads explicitly use unadjusted prices, repair enabled, timezone retention, a timeout, and a flat single-symbol index. Rows retain timestamps and omit the separately adjusted-close column. Volatility is annualized for every requested interval, uses 252/5 for five-day bars, and scales intraday periods for extended-hours sessions. RSI uses the canonical Wilder simple-average seed followed by recursive smoothing, with defined zero-gain/loss behavior. When requested, option Greeks are theoretical European Black-Scholes estimates per share (theta per day; vega/rho per one percentage point); risk-free-rate metadata identifies the configured fallback.

uv sync --locked
uv run python stockflow.py

The server uses stdio. Yahoo Finance is an unofficial personal-use source and may be delayed, incomplete, rate-limited, missing fields, or structurally changed. Dividends and American-style early exercise are not modeled in Greeks. 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. To avoid a port collision when running multiple servers, set MCP_HOST_PORT before starting Compose, for example $env:MCP_HOST_PORT=8003. Stop and remove the container with docker compose down.

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 stockflow.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 branch coverage is gated at 90%. Set YFINANCE_LIVE=1 to opt into live shape smoke tests.