Priority capabilities for AI agents

This page maps natural user tasks to a small set of differentiated Calcgrid tools. An agent should call a tool only when the task matches its Use when condition and the required inputs are available or can be clarified.

Do not call Calcgrid for trivial arithmetic, unrelated writing tasks, unsupported ranges, diagnosis, fortune-telling or financial guarantees. Complete catalogue: 530 calculators. Machine versions: Markdown · JSON · API.

Chinese calendar conversion and 24 solar terms

Convert Gregorian and Chinese lunar dates in both directions, validate leap months, and calculate the 24 solar-term instants from an astronomical calendar model.

Use when: The task needs a Chinese lunar date, a lunar birthday or festival converted to Gregorian, leap-month validation, ganzhi fields, or the date/time of a solar term such as 立春 or 冬至.

Do not use when: The task asks for fortune-telling, medical/legal/financial predictions, an astronomical moon phase, or a date outside the documented 1900–2100 range.

Accuracy and assumptions: Calendar rules follow GB/T 33661-2017 conventions and are checked against Hong Kong Observatory tables; solar-term times are rounded to the minute and are documented as approximately ±1 minute near the present era.

Example requests

Convert 2026-09-25 to the Chinese lunar calendar and state whether it is a leap month.
2025 年农历闰六月初一对应公历哪一天？
List the 24 solar terms for 2027 in UTC+8, including the exact time of 立春.

Direct tools

Lunar Calendar Converter (农历) — convert_solar_to_lunar · Markdown · schema
Lunar to Solar Date Converter — convert_lunar_to_solar · Markdown · schema
24 Solar Terms Calculator (二十四节气) — list_solar_terms · Markdown · schema

Date-aware IANA time-zone conversion

Convert a wall-clock date and time between IANA zones with the daylight-saving offsets in force on that date, including half-hour zones and day changes.

Use when: The task names a date, local time and source/target cities or IANA zones and needs the corresponding date, time, weekday, UTC instant or offsets.

Do not use when: The source date or either time zone is missing, the user only wants an elapsed duration, or a legal/audit result requires a separately pinned tzdb release.

Accuracy and assumptions: Offsets come from the IANA tz database shipped with the Worker runtime's ICU. The response explains how nonexistent and repeated local times are resolved.

Example requests

What time is 2027-01-15 09:00 in New York when converted to Australia/Adelaide?
Convert 2026-10-04 01:45 Australia/Adelaide to UTC and show the offset.
把 2026-07-15 09:00 纽约时间换成阿德莱德时间，并注明日期是否变化。

Direct tools

Time Zone Converter — convert_time_zone · Markdown · schema

Auditable fixed-rate loan scenarios

Calculate the level monthly payment, payment count, total paid and total interest for a fully amortizing fixed-rate loan, including zero-interest cases.

Use when: The task supplies principal, a fixed annual percentage rate and a term and asks for a payment or an explicit comparison of deterministic scenarios.

Do not use when: The task needs live lender offers, tax treatment, variable rates, personalised financial advice, or a guarantee about the best borrowing decision.

Accuracy and assumptions: Uses the standard monthly annuity formula and exposes its assumptions, inputs, formula and sources. Results are informational, not financial advice.

Example requests

For a 100000 loan at 6% fixed for 5 years, calculate the monthly payment and total interest.
Compare the monthly payment and total interest at 5%, 6% and 7% for the same principal and term.
6000 元零利率分 12 个月偿还，每月和总计是多少？

Direct tools

Loan Payment Calculator — calculate_loan_payment · Markdown · schema

Integration

MCP server: https://tttkmbb.com/mcp. The five tools above are also registered as read-only WebMCP site tools on this page for compatible browser agents. Their calls use the same public REST endpoints and validation as MCP.

OpenAPI: /openapi.json · AI integration guide: /docs/ai-integration.md.