Holiday Calendar

Working · 1.9 s

com.modernmustardseed/holiday-calendarv1.0.1 Domain verified

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

Utilities

Source Website Registry entry

Maintain this server? Claim it

Try it

Call this server's tools from your browser. Nothing to install.

https://starter.modernmustardseed.com/holidays

Requests go through mcptry because browsers can't call most MCP servers directly. Header values are sent to the server for that request only and are never stored or logged.

Tool list from our last check. Connect live to refresh it.

add_business_days Read-only

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.

start_datestring, required

The date to count from. It is not counted itself, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.

business_daysinteger, required

Business days to move, -1000 to 1000. Negative counts backward. 0 returns the start date if it is a business day, otherwise the next one.

Tools (5)

add_business_days

read-only

Argument	Type	Description
start_date*	string	The date to count from. It is not counted itself, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.
business_days*	integer	Business days to move, -1000 to 1000. Negative counts backward. 0 returns the start date if it is a business day, otherwise the next one.

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "start_date",
    "business_days"
  ],
  "properties": {
    "start_date": {
      "type": "string",
      "maxLength": 40,
      "description": "The date to count from. It is not counted itself, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100."
    },
    "business_days": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": -9007199254740991,
      "description": "Business days to move, -1000 to 1000. Negative counts backward. 0 returns the start date if it is a business day, otherwise the next one."
    }
  }
}

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.

read-only

Argument	Type	Description
date*	string	The date to check, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "date"
  ],
  "properties": {
    "date": {
      "type": "string",
      "maxLength": 40,
      "description": "The date to check, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100."
    }
  }
}

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.

read-only

Argument	Type	Description
end_date*	string	Last date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.
start_date*	string	First date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "start_date",
    "end_date"
  ],
  "properties": {
    "end_date": {
      "type": "string",
      "maxLength": 40,
      "description": "Last date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100."
    },
    "start_date": {
      "type": "string",
      "maxLength": 40,
      "description": "First date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100."
    }
  }
}

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.

read-only

Argument	Type	Description
year*	integer	Calendar year, 2021 through 2100.

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "year"
  ],
  "properties": {
    "year": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": -9007199254740991,
      "description": "Calendar year, 2021 through 2100."
    }
  }
}

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.

read-only

Argument	Type	Description
count	integer	How many upcoming holidays to return, 1 to 11. Defaults to 1.
from_date	string	Start looking on this date, inclusive, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100.

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {
    "count": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": -9007199254740991,
      "description": "How many upcoming holidays to return, 1 to 11. Defaults to 1."
    },
    "from_date": {
      "type": "string",
      "maxLength": 40,
      "description": "Start looking on this date, inclusive, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100."
    }
  }
}