Calcgrid

Chinese Zodiac Calculator (生肖)

find_chinese_zodiac

Read-onlyIdempotent

Use this when you need someone's Chinese zodiac sign and element from a Gregorian birth date, especially for January–February births where the boundary matters, or the sign's traditional compatibility groups. 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 need a full Bazi chart with month, day and hour pillars (use bazi-four-pillars), or the Western star sign (use zodiac). What it computes: Finds the Chinese zodiac animal (生肖 shengxiao), sexagenary year (干支 ganzhi), stem element, yin/yang, nayin (纳音) and fixed element for a birth date, using either the Chinese New Year boundary or the 立春 (Lichun) boundary, plus the traditional relationship groups (六合, 三合, 六冲, 六害, 相刑) and 本命年 years. Inputs: birth_date (date); boundary (enum, optional); reference_year (integer, optional). Complete JSON argument examples: {"birth_date":"1990-02-10","boundary":"lunar_new_year","reference_year":2026} | {"birth_date":"1990-02-03","boundary":"lichun"} Outputs: zodiac, zodiac_cn, year_ganzhi, year_ganzhi_pinyin, year_english, stem_element, yin_yang, nayin, animal_fixed_element, year_used, chinese_new_year_date, lichun_datetime, boundary_note, benmingnian_years, secret_friend, trine_partners, clash, harm, punishment, age_in_reference_year [years], is_benmingnian_in_reference_year, reference_year_zodiac. Formula: year_used = Gregorian year, minus 1 when birth_date is before Chinese New Year (or before 立春 with boundary = lichun); ganzhi index = (year_used − 4) mod 60; animal = branch = index mod 12; 六合 partner = (13 − b) mod 12; 三合 = b ± 4; 六冲 = b + 6; 六害 partner = (7 − b) mod 12 Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/chinese-zodiac with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/lunar/chinese-zodiac.md

Input Schema

TableJSON Schema

Name	Required	Description	Default
`boundary`	No	Which event starts the zodiac year: Chinese New Year (popular usage, default) or 立春 around 4 February (astrological usage).	lunar_new_year
`birth_date`	Yes	Gregorian birth date (civil date in China Standard Time), 1900–2100.
`reference_year`	No	Optional Gregorian year for which to report the age and whether it is a 本命年.

Output Schema

TableJSON Schema

Name	Required	Description
`links`	No
`result`	Yes
`request`	Yes
`sources`	No
`success`	Yes
`version`	No
`freshness`	No
`timestamp`	Yes
`next_actions`	No
`service_version`	Yes	Deployed Calcgrid implementation version used for the result.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 27, 2026

addedOutput schema / properties / service_version

Added value: +{
+  "description": "Deployed Calcgrid implementation version used for the result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "success",
-  "request",
-  "result",
-  "timestamp"
-]New value: +[
+  "success",
+  "service_version",
+  "request",
+  "result",
+  "timestamp"
+]

Changed1 schema field changedSep 26, 2026

addedInput schema / examples

Added value: +[
+  {
+    "birth_date": "1990-02-10",
+    "boundary": "lunar_new_year",
+    "reference_year": 2026
+  },
+  {
+    "birth_date": "1990-02-03",
+    "boundary": "lichun"
+  }
+]

AddedSep 25, 2026
RemovedSep 25, 2026
First observedSep 25, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations (readOnly, idempotent), the description discloses boundary selection logic (lunar new year vs lichun), explains the 'year_used' calculation, lists all output fields, and provides a REST fallback URL. It also notes the formula behind the calculation, offering transparency about edge cases like January–February births. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is extensive but well-organized: usage first, exclusions, then computation details, inputs, examples, outputs, formula, and fallback. It is front-loaded with the 'Use this when' phrase. While it could be trimmed (e.g., the formula section is optional given the tool computes it), every section serves a purpose for a complex calculator, so it earns its length.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is complex with 19 output fields, boundary logic, and compatibility groups. The description covers all inputs, outputs, formula, examples, REST fallback, and documentation link. Given the output schema exists, nothing an agent needs to call it correctly is missing. Complete for a tool of this sophistication.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema already covers 100% of parameters with descriptions, and the description adds further value: it explains the boundary enum options (Chinese New Year vs Lichun), gives complete JSON examples for each boundary, and clarifies how reference_year is used (to report age and 本命年 status). This exceeds the schema's explanatory power.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'find someone's Chinese zodiac sign and element from a Gregorian birth date'. It explicitly differentiates from sibling tools by naming bazi-four-pillars and zodiac as alternatives for other needs. The 'Use this when' phrasing immediately clarifies the tool's scope.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit when-to-use ('Use this when you need someone's Chinese zodiac sign...') and when-not-to-use ('Do not use this when you need a full Bazi chart... or the Western star sign (use zodiac)'). Also instructs the agent to 'Call this tool directly' rather than compute from memory, providing clear behavioral guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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