qinisolabs/bizdays

**Verified business-day math for AI agents — holidays + per-country weekends, not guesses.**
*Verified, trustworthy data tools for AI agents. "Qiniso" means "truth" in Zulu.*
Website · npm · MCP endpoint · MCP Registry
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LLMs answer "what date is 5 business days after Dec 22nd in the UK?", "how many working days are in this month?", and "is Friday a working day in Saudi Arabia?" confidently and often **wrongly** — they miscount, forget public holidays, and assume every country's weekend is Saturday/Sunday. **bizdays** gives an agent the deterministic answer from real public-holiday calendars and per-country weekend rules, showing the weekend rule and the exact holidays it skipped.
Two things break naive business-day math, and bizdays fixes both: **weekends aren't Sat/Sun everywhere** (Fri/Sat in Saudi Arabia, Egypt & Israel; Fri in Iran; Sun in India; Sat/Sun in the UAE since 2022), and **"holiday" must mean a real day off** — off-the-shelf data counts observances like Valentine's Day and Christmas Eve, which are not days off.
> Counting the working days in a month, a frontier LLM with no tools is **wrong 63% of the time**, cold — and **23% across business-day questions** overall. **bizdays: 0%.**
Add it to Claude
Settings → Connectors → **Add custom connector**, and paste — no login, no key:
Stateless, reads no user data, requires no secrets. Prefer to run it locally over stdio? Add { "command": "npx", "args": ["-y", "@qinisolabs/bizdays"] } under mcpServers in your client config.
Use it as a library
Every tool is also a typed function — no MCP required:
Every function returns a rich result: the answer, the weekday, exactly which weekends and named holidays were skipped, the weekend rule and its source, and a confidence flag.
What it does — 6 tools
| Tool | What it answers |
| --- | --- |
| **add_business_days** | What date is N working days from a start date? (N may be negative) |
| **count_business_days** | How many working days between two dates? (endpoints inclusive by default) |
| **is_business_day** | Is this date a working day? If not, why (weekend / public holiday with its name)? |
| **next_business_day** | First working day strictly after a date |
| **previous_business_day** | Last working day strictly before a date |
| **country_rule** | The weekend rule + its source, whether holidays apply, and a confidence flag |
Public holidays for **206 countries** (and subdivisions) come from date-holidays, filtered to type: "public". Weekends come from **Unicode CLDR** via the runtime Intl API, plus a curated data/weekend-overrides.json correction layer (e.g. Bangladesh Fri/Sat, Nepal Sat-only) — the maintained data is the moat.
What it is *not*
- **Not all-holidays.** It counts weekends and **public** holidays only — not regional or optional observances. Pass company shutdowns or regional days via extraHolidays.