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Western Astrology MCP Server by RoxyAPI

Calculate synastry - Relationship compatibility analysis API

post_astrology_synastry
Read-only

Calculate complete synastry (relationship compatibility) between two natal charts using Western tropical astrology. Analyzes inter-chart aspects between all planets to determine romantic, friendship, and karmic compatibility. Returns compatibility score (0-100), detailed inter-aspects with strength ratings, harmonious vs challenging aspect counts, and relationship dynamics analysis. Perfect for dating apps, matrimonial sites, relationship counseling tools, and astrology compatibility features. Based on professional astrological techniques.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
langNoResponse 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
compactNoSet 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.
person1Yes
person2Yes
houseSystemNoHouse system for both natal charts. Placidus (default), Whole Sign, Equal, or Koch.placidus

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. Changed2 schema fields changed
    • changedInput schema / properties / lang / description
      Previous value: -"Response language (ISO 639-1). Supported: en, tr, de, es, hi, pt, fr, ru. Defaults to en. Languages without translations yet return English."New value: +"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."
    • changedInput schema / properties / lang / enum
      Previous value: -[
      -  "en",
      -  "tr",
      -  "de",
      -  "es",
      -  "hi",
      -  "pt",
      -  "fr",
      -  "ru"
      -]New value: +[
      +  "en",
      +  "tr",
      +  "de",
      +  "es",
      +  "hi",
      +  "pt",
      +  "fr",
      +  "ru",
      +  "zh-Hans",
      +  "zh-Hant"
      +]
  2. Changed4 schema fields changed
    • addedInput schema / examples
      Added value: +[
      +  {
      +    "person1": {
      +      "date": "1990-07-15",
      +      "latitude": 40.7128,
      +      "longitude": -74.006,
      +      "time": "14:30:00",
      +      "timezone": -5
      +    },
      +    "person2": {
      +      "date": "1990-07-15",
      +      "latitude": 40.7128,
      +      "longitude": -74.006,
      +      "time": "14:30:00",
      +      "timezone": -5
      +    }
      +  }
      +]
    • changedInput schema / properties / compact / description
      Previous value: -"Set true to receive the exact same data in a token-optimized shape that is cheaper for you to read: whitespace is stripped and every array of same-shaped objects is encoded columnar as {\"__cols\":[field names],\"__rows\":[[values]]}, so each field name is sent once instead of once per row. Fully lossless (no field or value is dropped or changed) and typically 40 to 52 percent fewer tokens on large results. Prefer true whenever token or inference cost matters. Default false returns standard indented JSON."New value: +"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."
    • changedInput schema / properties / person1 / properties / nodeType / description
      Previous value: -"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 what most Western software reports (Astrolabe, Cafe Astrology, TimePassages), which is why it is the default here; astro-seek and the Steven Forrest evolutionary school use mean, so pass \"mean\" to match those. 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\"."New value: +"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\"."
    • changedInput schema / properties / person2 / properties / nodeType / description
      Previous value: -"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 what most Western software reports (Astrolabe, Cafe Astrology, TimePassages), which is why it is the default here; astro-seek and the Steven Forrest evolutionary school use mean, so pass \"mean\" to match those. 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\"."New value: +"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\"."
  3. Changed2 schema fields changed
    • addedInput schema / properties / person1 / properties / nodeType
      Added value: +{
      +  "default": "true",
      +  "description": "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 what most Western software reports (Astrolabe, Cafe Astrology, TimePassages), which is why it is the default here; astro-seek and the Steven Forrest evolutionary school use mean, so pass \"mean\" to match those. 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\".",
      +  "enum": [
      +    "mean",
      +    "true"
      +  ],
      +  "example": "true",
      +  "type": "string"
      +}
    • addedInput schema / properties / person2 / properties / nodeType
      Added value: +{
      +  "default": "true",
      +  "description": "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 what most Western software reports (Astrolabe, Cafe Astrology, TimePassages), which is why it is the default here; astro-seek and the Steven Forrest evolutionary school use mean, so pass \"mean\" to match those. 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\".",
      +  "enum": [
      +    "mean",
      +    "true"
      +  ],
      +  "example": "true",
      +  "type": "string"
      +}
  4. Changed1 schema field changed
    • changedInput schema / properties / compact / description
      Previous value: -"Return the same data in a token-optimized compact shape (minified, with same-shaped arrays encoded columnar) to reduce LLM token cost. Lossless: no fields are dropped. Default false."New value: +"Set true to receive the exact same data in a token-optimized shape that is cheaper for you to read: whitespace is stripped and every array of same-shaped objects is encoded columnar as {\"__cols\":[field names],\"__rows\":[[values]]}, so each field name is sent once instead of once per row. Fully lossless (no field or value is dropped or changed) and typically 40 to 52 percent fewer tokens on large results. Prefer true whenever token or inference cost matters. Default false returns standard indented JSON."
  5. Changed1 schema field changed
    • addedInput schema / properties / compact
      Added value: +{
      +  "default": false,
      +  "description": "Return the same data in a token-optimized compact shape (minified, with same-shaped arrays encoded columnar) to reduce LLM token cost. Lossless: no fields are dropped. Default false.",
      +  "type": "boolean"
      +}
  6. Changed4 schema fields changed
    • changedInput schema / properties / person1 / properties / timezone / anyOf
      Previous value: -[
      -  {
      -    "maximum": 14,
      -    "minimum": -14,
      -    "type": "number"
      -  },
      -  {
      -    "pattern": "^[A-Za-z_]+(?:\\/[A-Za-z0-9_+-]+){0,2}$",
      -    "type": "string"
      -  }
      -]New value: +[
      +  {
      +    "maximum": 14,
      +    "minimum": -14,
      +    "type": "number"
      +  },
      +  {
      +    "type": "string"
      +  }
      +]
    • changedInput schema / properties / person1 / properties / timezone / description
      Previous value: -"Timezone: decimal hours from UTC (e.g. -5 for EST, 5.5 for IST) OR IANA name (e.g. \"America/New_York\", \"Asia/Kolkata\"). IANA strings are resolved to the DST-correct offset for the given date, so you can pass `cities[0].timezone` from /location/search directly."New value: +"Timezone: IANA name (e.g. \"America/New_York\", \"Europe/London\") OR decimal hours from UTC (e.g. -5 for EST, 1 for CET). IANA strings are resolved to the DST-correct offset for the given date, so you can pass `cities[0].timezone` from /location/search directly."
    • changedInput schema / properties / person2 / properties / timezone / anyOf
      Previous value: -[
      -  {
      -    "maximum": 14,
      -    "minimum": -14,
      -    "type": "number"
      -  },
      -  {
      -    "pattern": "^[A-Za-z_]+(?:\\/[A-Za-z0-9_+-]+){0,2}$",
      -    "type": "string"
      -  }
      -]New value: +[
      +  {
      +    "maximum": 14,
      +    "minimum": -14,
      +    "type": "number"
      +  },
      +  {
      +    "type": "string"
      +  }
      +]
    • changedInput schema / properties / person2 / properties / timezone / description
      Previous value: -"Timezone: decimal hours from UTC (e.g. -5 for EST, 5.5 for IST) OR IANA name (e.g. \"America/New_York\", \"Asia/Kolkata\"). IANA strings are resolved to the DST-correct offset for the given date, so you can pass `cities[0].timezone` from /location/search directly."New value: +"Timezone: IANA name (e.g. \"America/New_York\", \"Europe/London\") OR decimal hours from UTC (e.g. -5 for EST, 1 for CET). IANA strings are resolved to the DST-correct offset for the given date, so you can pass `cities[0].timezone` from /location/search directly."
  7. First observed

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 agent knows this is a safe, non-mutating operation. The description adds meaningful behavioral context beyond the annotations by disclosing the output contents: compatibility score (0-100), inter-aspect listings with strength ratings, harmonious vs. challenging counts, and relationship dynamics analysis. This is especially valuable because no output schema is provided, so the description is the only source of return semantics.

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 appropriately sized for a complex astrology tool, with the core purpose and key output benefits appearing in the first two sentences. The promotional closing sentences ('Perfect for dating apps...' and 'Based on professional astrological techniques') are somewhat optional but not misleading or bloated. Overall it is well-structured and front-loaded with the most decision-relevant information.

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?

Given the tool's complexity, nested input objects, and lack of an output schema, the description does a good job of covering the essential context: what is calculated, how, and what the response contains. The remaining gap is that it does not explicitly disambiguate from the closely related sibling post_astrology_compatibility_score or describe the exact output shape with field names, which could have improved completion for an agent. Still, it is sufficient for a strong first pass.

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?

The description does not explain individual parameter formats or expectations; it relies on the input schema to carry that load. The schema itself is rich, providing deep descriptions for person1/person2, lang, compact, and houseSystem. Since schema description coverage is around 60% and the description only adds context-level meaning ('between two natal charts') without parameter-specific help, it is not better than the baseline.

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 clearly states the tool calculates 'complete synastry (relationship compatibility) between two natal charts' using 'Western tropical astrology,' which is a specific verb, resource, and method. It also distinguishes itself from sibling tools like post_astrology_natal_chart (single chart) and post_astrology_compatibility_score (score-focused) by emphasizing detailed inter-chart aspect analysis and relationship dynamics. The title and description align tightly with the tool name.

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 provides clear use-case context, explicitly mentioning dating apps, matrimonial sites, relationship counseling tools, and astrology compatibility features. This tells an agent when this tool is relevant. However, it does not explicitly name sibling alternatives (e.g., post_astrology_compatibility_score for a simpler score, or post_astrology_composite for a merged chart) or state when not to use this tool, so it falls short of full explicit routing.

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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TDQS

A3.8/5.0
Disambiguation3/5

Most tools are scoped to a clearly distinct domain—moon phases, houses, returns, fixed stars, astrocartography—but several pairs overlap, notably synastry vs. compatibility_score and transits vs. transit_aspects. The descriptions are long and do help an agent choose, but the boundaries are not always obvious at the name level.

Naming Consistency4/5

Every tool follows the same snake_case get_astrology_/post_astrology_ prefix pattern, making the group predictable and readable. However, collection endpoints like get_astrology_planet_meanings_id and get_astrology_signs_id awkwardly combine plural collection and singular id naming, and names like calendar_year_month depart from the cleaner resource+suffix pattern.

Tool Count2/5

With 38 tools, this is well over the 25+ threshold and feels heavy for an agent to traverse. While Western astrology is a broad domain, several near-duplicate endpoints, especially synastry/compatibility and transits/transit_aspects, could be consolidated into fewer, more scoped tools.

Completeness5/5

The toolset is comprehensive, covering natal charts, relationships, transits, returns, progressions, aspects, houses, relocation, and reference data. It includes enough specialized endpoints for both casual horoscope use and in-depth astrological analysis, with no obvious dead ends for the stated domain.

Resources