Mesoamerican Astrology MCP Server by RoxyAPI

Mayan day sign for a date - Tzolkin calculator API

post_mesoamerican_astrology_mayan_tzolkin

Read-only

Mayan astrology day sign calculator: returns the Tzolkin day sign, the coefficient 1 to 13 and the trecena for any Gregorian date, under the correlation living daykeepers use, with a composed nawal reading. Built for Mayan zodiac apps, daily energy feeds and AI agents answering what is my Mayan sign. Classical Maya count only, with the correlation echoed on every response so a saved reading stays reproducible.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`date`	Yes	Date in YYYY-MM-DD format, in the PROLEPTIC GREGORIAN calendar, extended backwards unchanged through the 1582 reform. Years 1 to 4000 are accepted. A reference converter that switches to the Julian calendar below the reform will disagree with a date before 15 October 1582 by ten or eleven days; that is a difference of input convention rather than of arithmetic, and passing the Julian equivalent to such a tool reproduces these values exactly. A single-digit month or day is accepted and zero padded.
`lang`	No	Response language (BCP 47). Supported: en, tr, de, es, hi, pt, fr, ru, zh-Hans, zh-Hant. Defaults to en. Coverage varies by domain, and a field with no translation in the requested language returns English.	en
`compact`	No	Set true for the same data in a compact shape: arrays of same-shaped objects arrive columnar as {"__cols":[names],"__rows":[[values]]}. Lossless, typically 40 to 52 percent fewer tokens.
`correlation`	No	Which correlation constant ties the day count to a civil date. This is the single choice that shifts every value in the response, so it is a parameter rather than a hidden default, and the resolved value comes back under conventions. "gmt-584283" is the commonly accepted constant and the default, and it is the one the major institutional converter runs on. "martinez-hernandez-584281" sits two days earlier, "astronomical-584285" two days later, and "martin-skidmore-584286" three days later, each shifting the Long Count by exactly its difference in days. Four of the eight published constants are offered: the other four sit tens of thousands of days away and are of historical interest only. The 584281 constant is the Martínez Hernández correlation, after Juan Martínez Hernández.	gmt-584283

Output Schema

TableJSON Schema

Name	Required	Description	Default
`date`	Yes
`number`	Yes
`daySign`	Yes
`reading`	Yes
`trecena`	Yes
`conventions`	Yes
`daySignName`	Yes
`daySignKiche`	Yes
`daySignClassic`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "conventions": {
+      "properties": {
+        "correlation": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "correlation"
+      ],
+      "type": "object"
+    },
+    "date": {
+      "type": "string"
+    },
+    "daySign": {
+      "type": "string"
+    },
+    "daySignClassic": {
+      "type": "string"
+    },
+    "daySignKiche": {
+      "type": "string"
+    },
+    "daySignName": {
+      "type": "string"
+    },
+    "number": {
+      "type": "number"
+    },
+    "reading": {
+      "properties": {
+        "challenges": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "guidance": {
+          "type": "string"
+        },
+        "keynote": {
+          "type": "string"
+        },
+        "numberBand": {
+          "type": "string"
+        },
+        "numberReading": {
+          "type": "string"
+        },
+        "strengths": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "keynote",
+        "numberReading",
+        "strengths",
+        "challenges",
+        "guidance"
+      ],
+      "type": "object"
+    },
+    "trecena": {
+      "properties": {
+        "dayOfTrecena": {
+          "type": "number"
+        },
+        "number": {
+          "type": "number"
+        },
+        "rulingSign": {
+          "type": "string"
+        },
+        "rulingSignName": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "number",
+        "dayOfTrecena",
+        "rulingSign",
+        "rulingSignName"
+      ],
+      "type": "object"
+    }
+  },
+  "required": [
+    "daySign",
+    "daySignName",
+    "daySignClassic",
+    "daySignKiche",
+    "number",
+    "trecena",
+    "date",
+    "reading",
+    "conventions"
+  ],
+  "type": "object"
+}

First observedSep 6, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context by stating that the correlation is echoed on every response for reproducibility and that a composed nawal reading is included.

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?

Three dense sentences front-load the core result and use case without unnecessary padding. The 'Built for' clause earns its place by clarifying intended usage, and only minor redundancy with the title/name prevents a 5.

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

Completeness4/5

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

With an output schema, detailed parameter descriptions, and read-only annotations, the agent has enough to call the tool correctly. The only notable gap is the lack of explicit routing to sibling tools for different calendar needs.

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

Parameters3/5

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

Schema description coverage is 100%, and the schema entries for date, lang, compact, and correlation are already very detailed. The description adds little parameter-specific meaning beyond mentioning the correlation in prose, so the baseline 3 applies.

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?

States a specific verb ('returns') and resource ('Tzolkin day sign, the coefficient 1 to 13 and the trecena') for any Gregorian date. It also clarifies the use case ('what is my Mayan sign') and distinguishes itself from sibling list/daily/monthly tools by being a single-date calculator.

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

Usage Guidelines4/5

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

The description clearly scopes use to single-date Tzolkin queries for apps and AI agents, and 'Classical Maya count only' hints at a boundary. However, it does not explicitly name alternatives such as long_count_convert or chart/compatibility tools, nor state when not to use it.

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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