freebazi-mcp

freebazi-mcp

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:

npx freebazi-mcp

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "freebazi": {
      "command": "npx",
      "args": ["-y", "freebazi-mcp"]
    }
  }
}

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.

Links

• Interactive calculator, guides, and full charts: freebazi.com
• What is a Day Master: freebazi.com/day-master
• The Ten Gods explained: freebazi.com/ten-gods

Credits

City data from GeoNames (CC BY 4.0). Simplified to Traditional conversion via OpenCC.

License

MIT