Days, business days, holidays. Count the days between two dates, add days, weeks, months or business days to a date, and look up public holidays, with exact answers and a mini calendar.
https://plugins-worker.demos.42a.ai/date-calculator/mcpSettings → Security and login → Developer mode → chatgpt.com/plugins → + → paste the URL. After a tool change: Refresh, then a new chat.
| Prompt | Tool | Expected |
|---|---|---|
| How many business days are there between Oct 1 and Dec 31, 2026 in the US, including both dates? | days_between | Hero shows 63 business days out of 92 calendar days, skipping Veterans Day, Thanksgiving and Christmas (Columbus Day is bank-only nationally, so it is not skipped). |
| How many days until Christmas? | days_between | Hero shows 85 days until Christmas, counted from today (Thu, Oct 1, 2026 in New York). |
| What date is 10 working days after December 18, 2026 in England? | add_to_date | Wednesday, Jan 6, 2027: Christmas Day, the Boxing Day substitute (Dec 28) and New Year's Day are skipped. |
| What is the date 6 months after August 31, 2026? | add_to_date | Sunday, Feb 28, 2027 (February has no 31st), flagged as a weekend. |
| What are the public holidays in Bavaria in 2026, and when is the next one? | list_holidays | Lists 12 public holidays (9 national plus Epiphany, Corpus Christi and All Saints' Day for Bavaria); the next is German Unity Day, Sat Oct 3, in 2 days. Offers an .ics download. |
| What time is it in Tokyo when it is 3 PM in New York? | none | Converting clock times between time zones is not date arithmetic. |
| Add my dentist appointment on March 3 at 2 PM to my calendar. | none | Creating a calendar event is not counting days. |
| How old will I be in 2040 if I was born in 1990? | none | Simple year subtraction the model answers directly; no dates or holidays involved. |