fatenava-mcp

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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:

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

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

Codex CLI

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

Cursor / generic MCP client

{
  "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):

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

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

2. Structured fields:

{
  "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

{
  "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

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