astroway-mcp

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by astroway

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TypeScript

Remote

Harmonic Chart

astroway_specialized_harmonics

Read-onlyIdempotent

Generate a harmonic astrology chart from birth data by multiplying all planet longitudes by a chosen harmonic number (2–36).

Instructions

Calculate a harmonic chart by multiplying all planet longitudes by the given harmonic number (H2–H36).

[Group: Specialized Charts] [Endpoint: POST /v1/harmonics] [Cost: 20 credits (Tier 2)]

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "body": "<body>"
    },
    "name": "astroway_specialized_harmonics"
  }
}

Input Schema

Name	Required	Description	Default
`body`	Yes	Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as "Placidus" is refused, and the case matters because I and i are two different Sunshine systems.

Output Schema

Name	Required	Description	Default
`meta`	No
`input`	No
`houses`	No
`aspects`	No
`planets`	No
`chartSect`	No
`julianDay`	No
`houseAspects`	No
`siderealTime`	No
`harmonicNumber`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.6.1Nov 9, 2026

changedInput schema / properties / body / allOf

Previous value: -[
-  {
-    "additionalProperties": {
-      "anyOf": [
-        {},
-        {
-          "type": "null"
-        }
-      ]
-    },
-    "description": "Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single Swiss Ephemeris letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems.",
-    "properties": {
-      "ayanamsa": {
-        "description": "Sidereal school by name. Lahiri when omitted. Equivalent to ayanamsaId; send either.",
-        "enum": [
-          "fagan-bradley",
-          "lahiri",
-          "de-luce",
-          "raman",
-          "krishnamurti",
-          "kp",
-          "yukteshwar",
-          "jn-bhasin",
-          "true-citra",
-          "djwhal-khul"
-        ],
-        "type": "string"
-      },
-      "ayanamsaId": {
-        "type": [
-          "number",
-          "null"
-        ]
-      },
-      "city": {
-        "default": "",
-        "type": "string"
-      },
-      "cosmogram": {
-        "type": "boolean"
-      },
-      "date": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
-        "type": "string"
-      },
-      "houseSystem": {
-        "default": "P",
-        "enum": [
-          "P",
-          "K",
-          "R",
-          "C",
-          "E",
-          "W",
-          "B",
-          "M",
-          "O",
-          "A",
-          "T",
-          "V",
-          "D",
-          "F",
-          "G",
-          "H",
-          "I",
-          "i",
-          "L",
-          "N",
-          "Q",
-          "S",
-          "U",
-          "X",
-          "Y"
-        ],
-        "type": "string"
-      },
-      "latitude": {
-        "maximum": 90,
-        "minimum": -90,
-        "type": "number"
-      },
-      "longitude": {
-        "maximum": 180,
-        "minimum": -180,
-        "type": "number"
-      },
-      "name": {
-        "default": "",
-        "type": "string"
-      },
-      "time": {
-        "pattern": "^\\d{2}:\\d{2}(:\\d{2})?$",
-        "type": "string"
-      },
-      "timezone": {
-        "description": "IANA zone name such as Europe/Kyiv, or auto to look the zone up from latitude and longitude. The server takes the offset that zone kept at this local date and time, summer time included, and uses it in place of timezoneOffset. A clock time that happened twice takes the first occurrence; one skipped when clocks went forward takes the offset from before the change. Abbreviations such as EST are refused. Before 1970 the tz database is not reliable for every place, so send timezoneOffset when the local clock is known.",
-        "type": "string"
-      },
-      "timezoneOffset": {
-        "anyOf": [
-          {
-            "maximum": 14,
-            "minimum": -14,
-            "type": "number"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": 0,
-        "description": "Hours from UTC at the given moment, not minutes. Fractional zones are hours too: 5.5 for India, 5.75 for Nepal, -3.5 for Newfoundland. Defaults to 0, meaning UTC. Ignored when timezone is sent."
-      },
-      "zodiacType": {
-        "enum": [
-          "tropical",
-          "sidereal"
-        ],
-        "type": "string"
-      }
-    },
-    "required": [
-      "date",
-      "time",
-      "latitude",
-      "longitude"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": {
-      "anyOf": [
-        {},
-        {
-          "type": "null"
-        }
-      ]
-    },
-    "properties": {
-      "harmonic": {
-        "maximum": 180,
-        "minimum": 2,
-        "type": "integer"
-      }
-    },
-    "required": [
-      "harmonic"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": {
+      "anyOf": [
+        {},
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "description": "Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems.",
+    "properties": {
+      "ayanamsa": {
+        "description": "Sidereal school by name. Lahiri when omitted. Equivalent to ayanamsaId; send either.",
+        "enum": [
+          "fagan-bradley",
+          "lahiri",
+          "de-luce",
+          "raman",
+          "krishnamurti",
+          "kp",
+          "yukteshwar",
+          "jn-bhasin",
+          "true-citra",
+          "djwhal-khul"
+        ],
+        "type": "string"
+      },
+      "ayanamsaId": {
+        "type": [
+          "number",
+          "null"
+        ]
+      },
+      "city": {
+        "default": "",
+        "type": "string"
+      },
+      "cosmogram": {
+        "type": "boolean"
+      },
+      "date": {
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+        "type": "string"
+      },
+      "houseSystem": {
+        "default": "P",
+        "enum": [
+          "P",
+          "K",
+          "R",
+          "C",
+          "E",
+          "W",
+          "B",
+          "M",
+          "O",
+          "A",
+          "T",
+          "V",
+          "D",
+          "F",
+          "G",
+          "H",
+          "I",
+          "i",
+          "L",
+          "N",
+          "Q",
+          "S",
+          "U",
+          "X",
+          "Y"
+        ],
+        "type": "string"
+      },
+      "latitude": {
+        "maximum": 90,
+        "minimum": -90,
+        "type": "number"
+      },
+      "longitude": {
+        "maximum": 180,
+        "minimum": -180,
+        "type": "number"
+      },
+      "name": {
+        "default": "",
+        "type": "string"
+      },
+      "time": {
+        "pattern": "^\\d{2}:\\d{2}(:\\d{2})?$",
+        "type": "string"
+      },
+      "timezone": {
+        "description": "IANA zone name such as Europe/Kyiv, or auto to look the zone up from latitude and longitude. The server takes the offset that zone kept at this local date and time, summer time included, and uses it in place of timezoneOffset. A clock time that happened twice takes the first occurrence; one skipped when clocks went forward takes the offset from before the change. Abbreviations such as EST are refused. Before 1970 the tz database is not reliable for every place, so send timezoneOffset when the local clock is known.",
+        "type": "string"
+      },
+      "timezoneOffset": {
+        "anyOf": [
+          {
+            "maximum": 14,
+            "minimum": -14,
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": 0,
+        "description": "Hours from UTC at the given moment, not minutes. Fractional zones are hours too: 5.5 for India, 5.75 for Nepal, -3.5 for Newfoundland. Defaults to 0, meaning UTC. Ignored when timezone is sent."
+      },
+      "zodiacType": {
+        "enum": [
+          "tropical",
+          "sidereal"
+        ],
+        "type": "string"
+      }
+    },
+    "required": [
+      "date",
+      "time",
+      "latitude",
+      "longitude"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": {
+      "anyOf": [
+        {},
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "properties": {
+      "harmonic": {
+        "maximum": 180,
+        "minimum": 2,
+        "type": "integer"
+      }
+    },
+    "required": [
+      "harmonic"
+    ],
+    "type": "object"
+  }
+]

changedInput schema / properties / body / description

Previous value: -"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single Swiss Ephemeris letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."New value: +"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."

Addedv1.6.0Oct 24, 2026

TDQS

A3.5/5.0

Behavior4/5

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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds genuinely non-derivable operational context: the HTTP endpoint (POST /v1/harmonics) and the cost ('20 credits (Tier 2)'), which matters for a metered API. It does not discuss auth requirements or error conditions, keeping it short of a 5.

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 core sentence is front-loaded and the metadata lines are terse and scannable with no filler. The only real cost is the inaccurate harmonic range, which is a correctness issue rather than a verbosity one.

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 present, return values need not be explained, and the nested input schema fully specifies the birth-data requirements. The description covers the compute model, endpoint, and credit cost, so an agent has what it needs to invoke it correctly; only the missing usage context and the range mismatch keep it from a 5.

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 nested body schema exhaustively documents date, time, timezone, houseSystem, and coordinate conventions, so the schema carries the parameter burden. The description's only parameter-level contribution is the harmonic range, and its 'H2–H36' conflicts with the schema's minimum 2 / maximum 180, adding mild confusion rather than clarity. Baseline 3 for high coverage is appropriate.

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

Purpose4/5

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

The description names a specific verb and resource ('Calculate a harmonic chart') and explains the underlying operation ('multiplying all planet longitudes by the given harmonic number'), which is enough to distinguish it from siblings like draconic or heliocentric charts. It stops short of naming a concrete sibling alternative, and the stated range 'H2–H36' does not match the schema's harmonic maximum of 180, which slightly muddies the purpose statement.

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no exclusions, and no routing toward the closest sibling (e.g. astroway_cosmobiology_eight_harmonic_aspects or astroway_specialized_draconic). The '[Group: Specialized Charts]' label implies a category but gives no condition for picking this tool over another chart endpoint.

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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