alexsu1212/freebazi-mcp

**English** | 繁體中文
A Model Context Protocol server that computes a full Chinese **Bazi** (八字, Four Pillars of Destiny) chart from a birth date, time, and place.
It wraps the same calculation engine that powers **freebazi.com**: an offline engine that corrects for **True Solar Time** and historical **daylight saving**, and is cross-validated against established Bazi libraries. No API key, no network calls, everything runs locally.
What it returns
Give it a birth moment and a city, and compute_bazi_chart returns:
- The **Four Pillars** (Year, Month, Day, Hour), each as a Heavenly Stem and Earthly Branch
- Your **Day Master** (日干) and the **Ten Gods** (十神) of every character
- **Hidden Stems** (藏干), **Na Yin** (纳音), and the **Twelve Growth Stages** (十二长生)
- **Five Elements** distribution, both visible and including hidden stems
- **Shen Sha** (神煞) and **branch relations** (合冲刑害)
- **Luck Pillars** (大运) with the current period flagged, and the current year's pillar
- A link to the full interactive chart on freebazi.com
Install
Requires Node.js 18+.
Run directly with npx:
Claude Desktop
Add to your claude_desktop_config.json:
Other MCP clients (Cline, Continue, Cursor, etc.) take the same command / args.
Tools
compute_bazi_chart
Compute a full chart.
| Argument | Type | Notes |
|---|---|---|
| year, month, day | number | Birth date |
| hour, minute | number | Local clock time as recorded (omit if timeUnknown) |
| gender | "male" \| "female" | Needed for luck-pillar direction |
| city | string | e.g. "Taipei", "New York". Resolved to longitude + time zone for True Solar Time |
| longitude, utcOffset | number | Alternative to city |
| timeUnknown | boolean | Hour pillar becomes tentative |
| trueSolarTime | boolean | Default true |
| dayRule | "zi23" \| "midnight" | Day boundary, default 23:00 |
| yearRule | "lichun" \| "cny" | Year boundary, default Li Chun |
search_cities
Search about 490 major world cities by English or Chinese name. Returns each match's country, longitude, and IANA time zone, so you can pass an exact city to compute_bazi_chart.
Example
> Compute the Bazi chart for someone born 15 June 1990, 9:30 AM, in New York.
The server resolves New York, applies True Solar Time (9:30 AM becomes 8:34 AM, 56 minutes earlier, which shifts the Hour pillar), and returns the four pillars 庚午 壬午 辛亥 壬辰 with a Xin (辛) yin Metal Day Master, all Ten Gods, elements, luck pillars, and more.
Accuracy and honesty
Solar-term boundaries are computed from the sun's apparent longitude with standard astronomical formulas, and time zones (including historical daylight saving) are resolved from the IANA database. The engine's four pillars match established libraries character for character across thousands of test charts.
Bazi is a traditional framework for reflection on temperament, tendencies, and timing. This tool describes a chart; it does not predict events.