# Holiday Calendar Muse connector

From musedirectory.ai, the independent directory of Meta Muse connectors. Not affiliated with Meta.

## Holiday Calendar

U.S. federal holidays and business-day math for deadlines and schedules

- Record: https://musedirectory.ai/connector/holiday-calendar
- Category: Productivity
- Developer: Modern Mustard Seed (https://starter.modernmustardseed.com/docs/holidays)
- Muse status: Extra setup. Not in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
- Health: Working, 186ms, checked 2026-10-29T11:00:47Z
- Endpoint: https://starter.modernmustardseed.com/holidays
- Auth: No account needed; Pricing: unknown
- Screening: Screened, no issues found (2026-10-29T03:46:23Z)
- Source: Found in the official MCP Registry (com.modernmustardseed/holiday-calendar) https://registry.modelcontextprotocol.io/v0/servers?search=com.modernmustardseed%2Fholiday-calendar

Provides U.S. federal holidays with observed dates, checks whether dates are business days, and calculates business days between dates or from a starting point, skipping weekends and holidays.

Example request: "How many business days do I have to deliver this order by next Friday?"

How to connect: Not in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use Holiday Calendar to help me. It is a free service with an MCP server at https://starter.modernmustardseed.com/holidays. It does not need an API key. Ask me before you share anything with it." Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.

Tools:
- list_federal_holidays: List the eleven U.S. federal holidays for one calendar year (2021 through 2100): each holiday's name, its actual date and weekday, the date it is observed when it falls on a weekend (Saturday moves to the Friday before, Sunday to the Monday after), and the rule that sets it, from
- next_federal_holidays: Find the next one to eleven U.S. federal holidays observed on or after a date, with each one's observed date and how many calendar days away it is. Without from_date it starts from today's date in America/New_York and says which date it used.
- check_business_day: Check whether a date is a U.S. business day (a weekday that is not an observed federal holiday). Returns the weekday, the holiday observed that day if any, and the business days just before and just after it.
- add_business_days: Move a number of U.S. business days forward or backward from a date, skipping weekends and observed federal holidays, for due dates, delivery windows and notice periods. The start date is not counted: 1 business day after a Friday is the next Monday, or Tuesday when that Monday i
- count_business_days: Count the U.S. business days between two dates, both dates included, leaving out weekends and observed federal holidays. Returns the business day count, the weekend days, and each holiday that fell in the span. Spans up to 3,660 calendar days.

Screening checks:
- MCP handshake: pass (Answered in 357ms)
- Domain against threat feeds (Cloudflare security DNS): pass (starter.modernmustardseed.com not flagged)
- Published packages against the OSV malicious-package database: n/a (No npm or PyPI package published)
- Hidden instructions or invisible characters in tool text: pass (5 tools read, nothing found)
- Inputs asking for passwords, card numbers or seed phrases: pass (None found)
- Domain and redirects: pass (Domain registered 430 days ago)
- AI review of purpose and tool behavior: pass (No concerns)