Holiday Calendar

com.modernmustardseed/holiday-calendarVersion 1.0.1

U.S. federal holidays with observed dates and business-day math. Example from an open-source kit.

Status

Responds200 msNov 14, 2026, 14:06 UTCAnswered our handshake without sign-in.

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Last checked: Nov 14, 2026, 14:06 UTC
Latency: 200 ms
Remotes responding: 1 of 1
Sign-in: No sign-in
Hosting: Hosted outside the EU (detected)
Registry data as of: Nov 14, 2026, 22:14 UTC

Data from the official MCP Registry, checked by run.zero. How we check

Connect

Streamable HTTP

https://starter.modernmustardseed.com/holidaysResponds200 msNov 14, 2026, 14:06 UTC

No sign-in

Claude Code

claude mcp add --transport http holiday-calendar https://starter.modernmustardseed.com/holidays

Claude Desktop and claude.ai

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Settings > Connectors > Add custom connector
Name: holiday-calendar
Remote MCP server URL: https://starter.modernmustardseed.com/holidays

Cursor

{
  "mcpServers": {
    "holiday-calendar": {
      "url": "https://starter.modernmustardseed.com/holidays"
    }
  }
}

VS Code

code --add-mcp '{"name":"holiday-calendar","type":"http","url":"https://starter.modernmustardseed.com/holidays"}'

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Tools

5 tools

Tools of Holiday Calendar
	Description		Read-only	Idempotent	Open world
`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 is a holiday. Returns the resulting date and every holiday it skipped. Up to 1,000 business days either way.	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 is a holiday. Returns the resulting date and every holiday it skipped. Up to 1,000 business days either way.	No	Yes	Yes	No
`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.	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.	No	Yes	Yes	No
`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.	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.	No	Yes	Yes	No
`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 5 U.S.C. 6103. Use it to answer which days federal offices close in a year.	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 5 U.S.C. 6103. Use it to answer which days federal offices close in a year.	No	Yes	Yes	No
`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.	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.	No	Yes	Yes	No

Details

Registry status: Active
Published: Oct 12, 2026
Updated: Oct 12, 2026
Website: https://starter.modernmustardseed.com/docs/holidays⁠ (opens in a new tab)
Repository: https://github.com/ModernMustardSeed/small-business-mcp-starter⁠ (opens in a new tab)
Categories (suggested): CommunicationSuggested categories are assigned automatically from the registry text and may be wrong. Verified operators can correct them.
GDPR: Not declared

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