fatenava-mcp

Cast BaZi, Zi Wei Dou Shu, and Western astrology natal charts from any MCP-capable AI agent.

One tool, three deterministic engines, zero setup: no account, no API key, nothing stored. Powered by the free chart API of FateNava.

What it does

Give it a birth (date, time, place, gender) and it returns structured chart data from up to three systems:

System	What you get
BaZi 八字 (Four Pillars of Destiny)	Four pillars (stems & branches), Day Master, Five-Elements distribution — computed with True Solar Time correction from the birthplace longitude
Zi Wei Dou Shu 紫微斗數 (Purple Star Astrology)	Twelve palaces with major stars, Life Palace, transformations
Western natal chart	Tropical zodiac, Placidus houses: Ascendant, planets by sign/house, elements & modalities

The numbers are computed, not AI-generated — the same birth always produces the same charts. Interpretation is left to your AI agent (or to FateNava's free reading tools).

Quick start

Claude Code

Terminal

claude mcp add fatenava -- npx -y fatenava-mcp

Codex CLI

toml

# ~/.codex/config.toml
[mcp_servers.fatenava]
command = "npx"
args = ["-y", "fatenava-mcp"]

Cursor / generic MCP client

config.json

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

Tools

cast_chart — Cast BaZi (Four Pillars), Zi Wei Dou Shu, and Western astrology natal charts from one birth input. Deterministic computation with True Solar Time correction; supports one-line multilingual birth text or structured fields.

`cast_chart`

Two ways to describe the birth — pick one:

1. One-line text (easiest; the API parses date, time, place and gender, and resolves the city to coordinates + timezone):

config.json

{ "text": "1995-08-10 12:00 Taipei female" }

City names in English, Chinese, Japanese, or Korean are accepted.

2. Structured fields:

config.json

{
  "year": 1995, "month": 8, "day": 10, "hour": 12, "minute": 0,
  "gender": "female",
  "longitude": 121.5, "latitude": 25.04, "timeZoneId": "Asia/Taipei"
}

Optional:

systems: ["bazi", "ziwei", "astro"] — pick a subset to keep the response small (default: all three).
birthTimeKnown: false — when the exact hour is unknown. BaZi still returns three pillars; hour-dependent parts are omitted honestly instead of being guessed.

Response shape

JSON Config

{
  "birth": { "date": "1995-08-10", "time": "12:00", "gender": "female", "place": "…" },
  "timeKnown": true,
  "charts": {
    "bazi":  { "ok": true, "view": { "dayMaster": {…}, "fourPillars": […], … } },
    "ziwei": { "ok": true, "view": { "palaces": […], … } },
    "astro": { "ok": true, "view": { "ascendant": {…}, "bodies": […], … } }
  }
}

Field names are English; traditional terms (heavenly stems, earthly branches, palace and star names) come in their native Chinese characters — ask your agent to translate them for the user.

Notes & principles

Free & anonymous. The underlying endpoint requires no login and stores nothing.
Deterministic. Charts are calculated by tested engines; the AI layer only interprets.
Honest about limits. Unknown birth time degrades gracefully instead of inventing an hour. Charts describe tendencies and themes — not fixed fate. Not medical, legal, or financial advice.
Learn the concepts: What is BaZi? · What is a natal chart? · What is Zi Wei Dou Shu?
Full readings, compatibility (synastry / 合婚) and AI Q&A: fatenava.com

Development

Terminal

npm install
npm run build
node dist/index.js   # speaks MCP over stdio

FATENAVA_API_BASE env var overrides the API origin (for testing).

License

MIT