public-holidays — a Hermes plugin

Public holidays for 200+ countries and their regions, plus workday checks, workday counts and deadline math, as Hermes Agent tools.

Language models are unreliable at calendar arithmetic ("what is 10 working days after 23 December in Bavaria?"). This plugin fetches the holiday list once per country and year and does the counting in code.

Tools

Toolset public_holidays:

Tool	What it does
`holidays_list`	Holidays of a country (optionally one region) for a year: date, weekday, local and English name, regions, types
`workday_check`	Is a date a working day? Weekday, weekend flag, holiday names. Without a region it also reports regional holidays that were not applied
`workdays_count`	Working days between two dates (both inclusive), plus the holidays that fell on weekdays
`workdays_add`	The date N working days after (or before, with a negative N) a start date; the start date is not counted

Common arguments:

country: ISO 3166-1 alpha-2 code (DE, AT, CH, US, GB, …)
subdivision (optional): ISO 3166-2 region (DE-NI, DE-BY, US-CA, or just NI together with country: DE). Without it only nationwide holidays count as days off, and results say so.
weekend (optional): weekday names, default ["Saturday", "Sunday"]
types (optional): which holiday types count, default ["Public"] (also Bank, School, Authorities, Optional, Observance)

Example prompts:

"Is 4 June 2026 a working day in North Rhine-Westphalia?"
"How many working days are in December 2026 in Lower Saxony?"
"The notice period is 15 working days from today, Bavaria. What's the last day?"
"List the public holidays in Austria next year."

Install

hermes plugins install public-holidays      # once it is in the catalog
# or directly from this repository
hermes plugins install https://github.com/Akloenx123/hermes-public-holidays
hermes plugins enable public-holidays

No API key, no configuration, no Python dependencies (standard library only). Requires Hermes 0.21 or newer.

Disclosure

Network: HTTPS GET requests to https://date.nager.at/api/v3/PublicHolidays/<year>/<country> (Nager.Date, a free public holiday API). Only the country code and year are sent; no dates, prompts or personal data. Redirects are not followed, each request times out after 10 seconds and responses over 1 MB are refused.
Storage: none on disk. Fetched holiday lists are cached in memory for the life of the process.
No credentials, shell commands, subprocesses, background tasks, hooks, telemetry or self-updating code.

Data and limits

Holiday data is whatever Nager.Date publishes; it covers roughly the years 2000–2098 and the countries listed at https://date.nager.at/Country. For a country or year it does not cover the tools return an error instead of an empty calendar, so a missing data set never turns holidays into workdays. Check results for legal deadlines against an official source.
"Workday" means not a weekend day and not a holiday of the selected types. Company holidays, half days (24/31 December) and bridge days are not modelled.
workdays_count covers at most ~10 years per call, workdays_add at most ±2000 working days.

Development

python -m pytest tests                    # offline, uses a recorded Nager.Date response
HOLIDAYS_LIVE=1 python -m pytest tests    # also checks the live API
hermes plugins validate . --install-deps  # the check the Hermes plugin catalog runs

License

MIT, see LICENSE.

public-holidays

What it adds

Tools 4

README