AstroWay Astrology API (full catalogue)

Moon Void-of-Course

astroway_calendar_moon_voc

Read-onlyIdempotent

Find Moon void-of-course periods within a date range. The Moon is VOC from its last aspect until it enters the next sign.

[Group: Calendar & Cycles] [Endpoint: POST /v1/moon-voc] [Required: date, time] [Cost: 10 credits (Tier 1)]

Input Schema

Name	Required	Description
`date`	Yes
`time`	Yes
`fields`	No	Compact mode: comma-separated dotted paths to keep, relative to `data`, e.g. "planets.name,planets.longitude,houses.cusp". Omit for the whole response.
`timezone`	No	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.
`precision`	No	Compact mode: round fractional numbers to this many decimals. Longitudes carry 14 by default; 2 is finer than any chart is drawn.
`rangeDays`	No
`timezoneOffset`	No	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.

Output Schema

Name	Required	Description	Default
`periods`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedNov 7, 2026

changedOutput schema / properties / periods / anyOf

Previous value: -[
-  {
-    "items": {
-      "anyOf": [
-        {
-          "additionalProperties": {},
-          "properties": {
-            "durationHours": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "endDate": {
-              "anyOf": [
-                {
-                  "type": "string"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "endJd": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "lastAspect": {
-              "anyOf": [
-                {
-                  "additionalProperties": {},
-                  "properties": {
-                    "aspectName": {
-                      "anyOf": [
-                        {
-                          "type": "string"
-                        },
-                        {
-                          "type": "null"
-                        }
-                      ]
-                    },
-                    "aspectSymbol": {
-                      "anyOf": [
-                        {
-                          "type": "string"
-                        },
-                        {
-                          "type": "null"
-                        }
-                      ]
-                    },
-                    "planetId": {
-                      "anyOf": [
-                        {
-                          "type": "number"
-                        },
-                        {
-                          "type": "null"
-                        }
-                      ]
-                    }
-                  },
-                  "type": "object"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "nextSignIndex": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "startDate": {
-              "anyOf": [
-                {
-                  "type": "string"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "startJd": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            }
-          },
-          "type": "object"
-        },
-        {
-          "type": "null"
-        }
-      ]
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "anyOf": [
+        {
+          "additionalProperties": {},
+          "properties": {
+            "durationHours": {
+              "type": [
+                "number",
+                "null"
+              ]
+            },
+            "endDate": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "endJd": {
+              "type": [
+                "number",
+                "null"
+              ]
+            },
+            "lastAspect": {
+              "anyOf": [
+                {
+                  "additionalProperties": {},
+                  "properties": {
+                    "aspectName": {
+                      "type": [
+                        "string",
+                        "null"
+                      ]
+                    },
+                    "aspectSymbol": {
+                      "type": [
+                        "string",
+                        "null"
+                      ]
+                    },
+                    "planetId": {
+                      "type": [
+                        "number",
+                        "null"
+                      ]
+                    }
+                  },
+                  "type": "object"
+                },
+                {
+                  "type": "null"
+                }
+              ]
+            },
+            "nextSignIndex": {
+              "type": [
+                "number",
+                "null"
+              ]
+            },
+            "startDate": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "startJd": {
+              "type": [
+                "number",
+                "null"
+              ]
+            }
+          },
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

First observedOct 5, 2026

TDQS

A3.5/5.0

Behavior3/5

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real operational context — endpoint, credit cost (10 credits, Tier 1) and required inputs — but says nothing about what the periods look like, whether the range is capped at 366 days, or how the required 'time' affects the search window.

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?

Two tight sentences that lead with the action and follow with the definition, plus a compact metadata block giving group, endpoint, required fields and cost. Nothing is padded, though the bracketed metadata is boilerplate shared across the toolset.

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?

An output schema exists, so return values need not be described, and the safety profile is carried by annotations. What remains missing is small but real: how rangeDays defaults and whether the date/time pair anchors the start of the scan.

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 coverage is 57%: timezone, timezoneOffset, fields and precision are documented in the schema, but date, time and rangeDays have only type/pattern/bounds. The phrase 'within a date range' hints at rangeDays but the description never explains that date+time is the window start or what default range applies, so it only partially compensates for the coverage gap.

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?

States a specific verb and resource ('Find Moon void-of-course periods') and even defines the concept ('from its last aspect until it enters the next sign'), so the agent knows exactly what is returned. It does not, however, name the nearby siblings (astroway_calendar_moon_phase, astroway_calendar_moon_aspects, astroway_calendar_lunar_calendar) or say how it differs from them.

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

Usage Guidelines3/5

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

Usage is only implied by 'within a date range' and the bracketed 'Required: date, time' line. There is no statement of when to prefer this over the Moon phase or Moon aspects tools, and no prerequisites or exclusions.

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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