marketcal
An MCP server that gives AI agents correct trading-day and settlement math. LLMs are unreliable at "is the market open today?" and "what's the T+1 settlement date?" — this gets it exactly right, with no API key and no external calls.
| Tool | Does | | --- | --- | | is_trading_day | Is a date a trading day? (weekend/holiday aware, with reason) | | next_trading_day / previous_trading_day | Nearest trading day after/before a date | | settlement_date | T+N settlement date (advance N trading days; T+1 is the modern default) | | trading_days_between | Count trading days in an inclusive date range | | market_holidays | List an exchange's holidays for a given year |
Exchanges: NYSE, NASDAQ (US), LSE (London), XETRA (Frankfurt), GENERIC (weekends only).
Why it's correct
Holidays are computed from each exchange's rules — nth-weekday-of-month, Good Friday via the Gregorian Easter algorithm, and the exchange's weekend-observation rules (e.g. US: Saturday → Friday, Sunday → Monday; UK substitute days; XETRA closes Christmas Eve & New Year's Eve). No hardcoded date tables to rot — it stays right for any year.
Use it
npm install && npm run build && npm start
# or: npm run dev (no build step)
npm run inspect # try the tools in the MCP InspectorConnect to Claude Desktop / Cursor:
{
"mcpServers": {
"marketcal": {
"command": "npx",
"args": ["-y", "mcp-marketcal"]
}
}
}Then ask: "Using marketcal, what's the T+1 settlement date for a trade on 2026-07-02 on NYSE?" → 2026-07-06 (July 3 is the observed Independence Day holiday, July 4–5 is the weekend).
Notes & scope
- Covers full-day market closures. Early-close (half) days are not modelled in v0.1.
- All dates are calendar dates in
YYYY-MM-DD(UTC), no intraday/timezone logic. settlement_dateadvances trading days (the standard settlement convention).- Roadmap: more exchanges (TSX, Euronext, JPX, HKEX), early-close days, and a hosted HTTP +
usage-billed tier (x402 / Stripe) for high-volume agents.
License
MIT
