# calculate_bazi_four_pillars

Use this when you need the four stem-branch pillars (年柱 月柱 日柱 时柱) of a birth moment, the day master and its ten-god relations, element balance, or the start age and sequence of the 大运 luck pillars. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery. Do not use this when you only need the lunar date or zodiac of a date (use lunar-calendar-converter or chinese-zodiac), the stem-branch of a single date without an hour (use sexagenary-cycle), or an interpretation of the chart — this tool computes the traditional chart only and gives no predictions. What it computes: Builds the Bazi (八字, Bāzì) / Four Pillars (四柱) chart of a birth date and time: year pillar by 立春 (Lìchūn), month pillar by the 节 (jié) solar terms, day pillar from the sexagenary day count, hour pillar by the 五鼠遁 (Wǔshǔdùn) rule, plus day master, five-element counts, ten gods (十神), hidden stems (藏干), 纳音 (nàyīn), void branches (空亡) and the ten-year luck pillars (大运). Inputs: birth_date (date); birth_time (string); sex (enum); utc_offset_hours (number, h, optional); longitude_degrees (number, °, optional); late_zi_next_day (boolean, optional); include_hidden_stems (boolean, optional). Complete JSON argument examples: {"birth_date":"1990-05-17","birth_time":"08:30","sex":"male","utc_offset_hours":8} | {"birth_date":"2000-01-01","birth_time":"00:30","sex":"female","utc_offset_hours":8} Outputs: bazi_chart, year_pillar, month_pillar, day_pillar, hour_pillar, pillars_pinyin, pillars_english, day_master, zodiac, five_element_counts, missing_elements, dominant_element, ten_gods, hidden_stems, nayin, void_branches, luck_direction, luck_start_age, luck_start_age_years [years], luck_pillars, lunar_birth_date, solar_term_context, time_used, notes. Formula: year = solarYearAtLichun(birth instant); month stem = ((year stem mod 5) × 2 + 2 + months since 寅) mod 10; day index = (JDN + 49) mod 60; hour stem = ((day stem mod 5) × 2 + hour branch) mod 10; hour branch = floor(((hour + 1) mod 24) / 2); true solar time = clock + (longitude − 15 × utc_offset) × 4 min + equation of time; 起运 years = days to 节 / 3 Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/bazi-four-pillars with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/lunar/bazi-four-pillars.md

Agent View of the PolicyLayer registry record for `calculate_bazi_four_pillars`. HTML page: https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-bazi-four-pillars

## Facts

- Tool: `calculate_bazi_four_pillars`
- Server: Calcgrid (`https://tttkmbb.com/mcp`) — https://policylayer.com/tools/com-tttkmbb-calcgrid.md
- Homepage: https://github.com/https://tttkmbb.com/mcp
- Risk category: Execute (High risk)
- Registry record: grade D, identity unverified
- Server auth posture: open
- Server CORS policy: *
- Server rate-limited: no
- Parameters: 7 (3 required)
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `sex` | string | yes | Sex, used only for the direction of the luck pillars (阳年男/阴年女 forward, 阴年男/阳年女 backward). |
| `birth_date` | string | yes | Gregorian civil date of birth in the local clock time of the birthplace (1900–2100). |
| `birth_time` | string | yes | Local clock time of birth, 24-hour HH:MM. 23:00–00:59 is 子时 (Zǐ hour). |
| `late_zi_next_day` | boolean | no | true: 23:00–23:59 belongs to the next day's 子时 and the day pillar advances at 23:00. false: 晚子时 convention — the day pillar stays, only the hour stem is taken f |
| `utc_offset_hours` | number | no | Time-zone offset of birth_time in hours (China Standard Time = 8; use the historical zone in force at birth). Unit: h. |
| `longitude_degrees` | number | no | Optional east-positive longitude. When given, the clock time is converted to true solar time: correction = (longitude − 15 × utc_offset_hours) × 4 min + equatio |
| `include_hidden_stems` | boolean | no | Add the hidden stems (藏干) of the four branches to the element count with weights 1.0 (main), 0.5 (middle) and 0.3 (residual). |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "calculate_bazi_four_pillars",
    "arguments": {
      "sex": "<sex>",
      "birth_date": "<birth_date>",
      "birth_time": "<birth_time>"
    }
  }
}
```

## Why calculate_bazi_four_pillars is rated High

calculate_bazi_four_pillars triggers real processes with real consequences. An agent gone sideways doesn't fire it once. It starts dozens of builds, sends mass notifications, or burns through compute before anyone looks up.

## Use case

AI agents invoke calculate_bazi_four_pillars to trigger actions in Calcgrid. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Calcgrid:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "calculate_bazi_four_pillars": {
      "limits": [
        {
          "counter": "calculate_bazi_four_pillars_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

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## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-tttkmbb-calcgrid · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-tttkmbb-calcgrid