Astro Agents - deterministic Western + Vedic astrology

Nakshatras

nakshatras

Read-onlyIdempotent

Vedic astrology nakshatras: the sidereal nakshatra, pada and lord of every graha, plus the janma nakshatra with gana, yoni, nadi and varna. The 27 lunar mansions for each of the 9 grahas at a moment (Lahiri by default, 6 ayanamsas), with the birth star's attributes used in matching. Or pass 'longitude_sidereal' for a direct lookup. Deterministic (JPL DE440, no LLM); every result carries meta.result_sha256. Price $0.02 per call via REST POST https://astro-agent.dev/v1/vedic/nakshatra (x402 or MPP); your first 3 calls are free here.

Input Schema

Name	Required	Description	Default
`date`	No	YYYY-MM-DD (use with 'time' instead of 'datetime').
`time`	No	HH:MM or HH:MM:SS, 24 h. Omit if unknown (computed at 12:00 with a TIME_UNKNOWN warning).
`options`	No	Optional calculation settings; every default is the common Parashari convention.
`datetime`	No	Local birth date-time, ISO 8601: '1990-05-15T14:30' (local clock time at the place) or with an explicit offset '1990-05-15T14:30:00+02:00'. Alternative: 'date' + 'time'.
`latitude`	No	Decimal degrees, north positive.
`timezone`	No	IANA zone, e.g. 'Asia/Kolkata'. Optional: resolved from the coordinates, with the historical offset (DST, Local Mean Time) of that date.
`longitude`	No	Decimal degrees, east positive.
`time_basis`	No	What the given clock time is: civil wall-clock (default), UTC, Local Mean Time, or true (apparent) solar time.	civil
`ambiguous_time`	No	Which occurrence to use when a local time happens twice (DST fall-back).	earlier
`longitude_sidereal`	No	Optional direct lookup, degrees 0-360.

Output Schema

Name	Required	Description
`meta`	Yes	Provenance of the result.
`result`	Yes	The calculation result.
`endpoint`	Yes	The REST route that computed it, e.g. 'western/natal'.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 6, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "endpoint": {
+      "description": "The REST route that computed it, e.g. 'western/natal'.",
+      "type": "string"
+    },
+    "meta": {
+      "description": "Provenance of the result.",
+      "properties": {
+        "astronomy_library": {
+          "description": "Astronomy library and version.",
+          "type": "string"
+        },
+        "compute_ms": {
+          "description": "Computation time in milliseconds.",
+          "type": "number"
+        },
+        "computed_at": {
+          "description": "When it was computed (UTC, ISO 8601).",
+          "type": "string"
+        },
+        "deterministic": {
+          "description": "Always true: same input, same result.",
+          "type": "boolean"
+        },
+        "engine": {
+          "description": "Engine name and version.",
+          "type": "string"
+        },
+        "ephemeris": {
+          "description": "Ephemeris used (NASA/JPL DE440).",
+          "type": "string"
+        },
+        "frame": {
+          "description": "Reference frame of the positions.",
+          "type": "string"
+        },
+        "input_sha256": {
+          "description": "SHA-256 of the canonical input.",
+          "type": "string"
+        },
+        "llm_used": {
+          "description": "Always false: no language model is involved.",
+          "type": "boolean"
+        },
+        "payment": {
+          "description": "How this call was paid: protocol ('free' or 'none'), price and the free calls remaining.",
+          "type": "object"
+        },
+        "reproducibility": {
+          "description": "How to reproduce and check this result.",
+          "type": "string"
+        },
+        "result_sha256": {
+          "description": "SHA-256 of the canonical 'result'; check it with verify_result_hash.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "engine",
+        "deterministic",
+        "llm_used",
+        "input_sha256",
+        "result_sha256"
+      ],
+      "type": "object"
+    },
+    "result": {
+      "description": "The calculation result.",
+      "properties": {
+        "grahas": {
+          "description": "Nakshatra and pada of each of the nine grahas, with lord and deity.",
+          "type": "array"
+        },
+        "janma_nakshatra": {
+          "description": "The Moon's (birth) nakshatra: name, index, pada, lord, deity and fraction elapsed.",
+          "type": "object"
+        },
+        "janma_nakshatra_attributes": {
+          "description": "Yoni, gana, nadi and lord of the birth nakshatra.",
+          "type": "object"
+        },
+        "settings": {
+          "description": "Settings applied: sidereal zodiac, ayanamsa and lunar node type.",
+          "type": "object"
+        },
+        "subject": {
+          "description": "The resolved input: 'time' (local input, time zone and historical UTC offset, UT, Julian days, Delta T) and, when given, 'location' (latitude, longitude).",
+          "type": "object"
+        },
+        "warnings": {
+          "description": "Notes on the input or the calculation (for example an assumed noon for an unknown birth time). Present only when there is something to say.",
+          "type": "array"
+        }
+      },
+      "required": [
+        "subject",
+        "settings",
+        "janma_nakshatra",
+        "janma_nakshatra_attributes",
+        "grahas"
+      ],
+      "type": "object"
+    }
+  },
+  "required": [
+    "endpoint",
+    "result",
+    "meta"
+  ],
+  "type": "object"
+}

Changed3 schema fields changedOct 5, 2026

addedInput schema / properties / options / description

Added value: +"Optional calculation settings; every default is the common Parashari convention."

addedInput schema / properties / options / properties / ayanamsa / description

Added value: +"Sidereal reference (ayanamsa). Default 'lahiri' (Chitrapaksha), the Indian standard."

addedInput schema / properties / options / properties / include_outer_planets / description
```
Added value: +"Also return Uranus, Neptune and Pluto (not used in classical Jyotish)."
```

First observedOct 3, 2026

TDQS

A4.3/5.0

Behavior5/5

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), but the description adds substantial behavior beyond them: deterministic JPL DE440 computation with no LLM, a result_sha256 for verification, timezone/historical-offset resolution, and a pricing/transport model ($0.02 via REST POST, x402 or MPP, first 3 calls free). These are exactly the operational facts an agent needs and cannot get from annotations.

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 what the tool computes, followed by defaults, determinism and pricing. It is dense and condensed into one long paragraph with heavy parentheticals, and the pricing/endpoint sentence is more sales than semantics, but nearly every clause carries 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?

With an output schema present, return values need not be explained, and 10 parameters are fully schema-documented. The description adds determinism, hash, timezone resolution and the direct-lookup path, which is enough for correct invocation; the only soft spot is that the interaction between datetime+coords and longitude_sidereal (when each is expected) is only implied.

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% (ayanamsa default, node_type, house_system, time_basis, ambiguous_time, lat/long all documented in-schema), so baseline is 3. The description reinforces the ayanamsa set and, usefully, explains that longitude_sidereal is a direct-lookup path that bypasses the date/place route — a semantic addition, but not enough to lift beyond 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?

States a specific verb+resource: it returns the sidereal nakshatra, pada and lord for each of the 9 grahas, plus the janma nakshatra attributes (gana, yoni, nadi, varna). It also names the scope (27 lunar mansions, Lahiri default, 6 ayanamsas) and an alternate input mode (longitude_sidereal), so an agent can distinguish it from kundli/planet_positions without opening the schema.

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?

Gives clear context for use — nakshatra data at a moment, and the birth star's attributes 'used in matching' — and routes the agent to an alternate mode when it has a sidereal longitude instead of a date/place. It stops short of naming sibling tools (gun_milan, kundli, planet_positions) or stating when NOT to use it, so no explicit alternatives comparison.

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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