RoxyAPI Astrology MCP server

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TypeScript

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Solar arc directions calculator - directed chart at one degree per year

post_astrology_solar_arc

Read-only

Calculate a solar arc directed chart from birth data to a target date, advancing natal points to support predictive timing of major life events.

Instructions

Calculate a solar arc directed chart for any birth moment and target date. The solar arc is the secondary-progressed Sun longitude minus the natal Sun longitude, about one degree for each year of life, and every natal point including the Ascendant and Midheaven is advanced forward by that same arc. Returns the solar arc, each directed point with its natal and directed longitude, zodiac sign, degree, and a plain language interpretation, for predictive astrology apps timing major life events. Built on accurate tropical chart positions, no astronomy expertise needed.

Input Schema

Name	Required	Description	Default
`date`	Yes	Birth date in YYYY-MM-DD format. Determines planetary positions for the specific calendar day.
`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
`time`	Yes	Birth time in 24-hour HH:MM:SS format. Determines the Ascendant (rising sign) and house cusps. Use 12:00:00 if unknown.
`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.
`latitude`	Yes	Birth location latitude in decimal degrees (-90 to 90). Positive = North, negative = South.
`nodeType`	No	Lunar node convention. "mean" is the smoothed average node, which always moves retrograde; "true" is the osculating node, which tracks the real perturbed node, oscillates up to about 1.5 degrees either side of the mean on a 173-day cycle, and can briefly turn direct. Neither is more correct and they almost always fall in the same sign. Applies to the North and South Node. True is the osculating node and the default, because it is what most Western chart software reports; mean is the smoothed node preferred by several evolutionary schools, so pass "mean" to match one. Nothing else in the chart changes, and the two agree on the sign except when the node sits within about 1.8 degrees of a cusp. Defaults to "true".	true
`timezone`	Yes	Timezone: an IANA name (e.g. "America/New_York", "Europe/London", or `cities[0].timezone` from /location/search) or decimal hours from UTC (e.g. -5 for EST, 5.5 for IST). An IANA name is resolved to the offset in force at the given date and time.
`longitude`	Yes	Birth location longitude in decimal degrees (-180 to 180). Positive = East, negative = West.
`targetDate`	Yes	Date to direct the chart to, in YYYY-MM-DD format. Every natal point is advanced by the solar arc accumulated from birth to this date, about one degree for each year of life.

Output Schema

Name	Required	Description	Default
`summary`	Yes
`directed`	Yes
`solarArc`	Yes
`targetDate`	Yes
`birthDetails`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.1.2Oct 5, 2026

changedInput schema / examples

Previous value: -[
-  {
-    "date": "1990-07-15",
-    "latitude": 40.7128,
-    "longitude": -74.006,
-    "targetDate": "2025-07-15",
-    "time": "14:30:00",
-    "timezone": -5
-  }
-]New value: +[
+  {
+    "date": "1990-07-15",
+    "latitude": 40.7128,
+    "longitude": -74.006,
+    "targetDate": "2025-07-15",
+    "time": "14:30:00",
+    "timezone": "America/New_York"
+  }
+]

changedInput schema / properties / timezone / example

Previous value: --5New value: +"America/New_York"

First observedv0.1.0Oct 4, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds useful non-obvious detail: the exact arc computation, that every natal point including Ascendant and Midheaven is advanced, and what the response contains. It omits any note on rate limits, precision limits, or timezone edge cases, which keeps 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?

Front-loaded with the core action and the arc definition before the return payload, which is the right ordering. It is somewhat padded with promotional clauses ('Built on accurate tropical chart positions, no astronomy expertise needed') that do not help invocation.

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 required-parameter set is fully covered by the schema. The description supplies the conceptual model needed to call the tool correctly; only the missing sibling differentiation keeps it from being fully complete.

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%, so every parameter is already documented in the schema, including targetDate's semantics. The description reinforces the targetDate concept ('about one degree for each year of life') but adds no syntax or format meaning beyond the schema. 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 and resource ('Calculate a solar arc directed chart') and defines the mechanism precisely: secondary-progressed Sun minus natal Sun, applied to every natal point. This clearly separates it from sibling predictive techniques such as post_astrology_progressions, post_astrology_profections, and post_astrology_transits.

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?

Offers a target use case ('predictive astrology apps timing major life events') but never states when to choose this over the closely related progression/profection/transit siblings, and gives no exclusions or prerequisites. Usage is implied rather than directed.

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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