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CycleCalcs Astronomy

by com.cyclecalcs

Mercury and Venus apparition events

astro_planet_events
Read-only

The apparition cycle of the inferior planets as dated events: inferior and superior conjunctions, greatest eastern and western elongations, peak brightness (a Venus-only event: Mercury's brightness peaks behind the Sun where it cannot be seen), and the rare transits across the Sun. With no dates it also reports where each body is in its cycle right now: morning star or evening star, the conjunctions bounding the current apparition, and the live elongation, phase, magnitude and apparent size. The right tool for "when does Venus become the morning star", "when is Venus brightest", or "Mercury's next greatest elongation". For tonight's visibility of all eight planets use astro_planet_board. Conjunction instants use the classical heliocentric convention, named on each event.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
tzNoIANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone.
endNoLast day of an explicit window, exclusive. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there.
latNoLatitude in decimal degrees, north positive. Send lat and lon together.
lonNoLongitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together.
dateNoAnchor instant; with no start/end the response covers the next full synodic cycle from here. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there.
kindsNoOptional filter of event kinds. Omit for all. peak_magnitude only ever fires for venus; the transit kinds are body-specific and genuinely rare.
placeNoPlace name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attribution field, which must be preserved when shown.
startNoFirst day of an explicit window (use with end). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there.
bodiesNoWhich inferior planets to report. Default both.
cursorNoOpaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataYesApparition events per planet in a date range: conjunctions, elongations, stations.
rightsNoEither unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown.
warningsNoMachine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded.
attributionNoThe credit line to display verbatim when rights is attribution_required.
next_cursorNoPresent only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page.
not_computedNoData this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists".

TDQS

A4.9/5.0
Behavior5/5

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

Adds important non-obvious behavior beyond readOnlyHint: peak_magnitude is Venus-only and Mercury's peak is unobservable because it is behind the Sun; transits are genuinely rare; conjunction instants use the classical heliocentric convention and are named on each event. This is context an agent needs to interpret results correctly.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three dense sentences cover the core capability, event list, both operating modes, example use cases, the sibling alternative, and a convention caveat. No wasted words; information is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter tool with multiple event kinds and two modes, the description captures the main functionality, the no-date live snapshot, event-specific exceptions, and the correct alternative. The output schema and rich input schema descriptions handle remaining details like pagination and date ranges.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema descriptions are already thorough and cover 100% of parameters. The description complements them by clarifying the behavior of 'kinds' (peak_magnitude only for Venus, transits body-specific) and by tying the 'with no dates' mode to the optional date/start/end parameters. This adds semantic value beyond the schema.

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 states 'The apparition cycle of the inferior planets as dated events' and enumerates specific event types (conjunctions, elongations, peak brightness, transits). It also distinguishes the no-date mode that reports current cycle state, and explicitly contrasts with astro_planet_board.

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

Usage Guidelines5/5

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

Explicitly provides use cases: 'The right tool for "when does Venus become the morning star", "when is Venus brightest", or "Mercury's next greatest elongation"' and a direct alternative: 'For tonight's visibility of all eight planets use astro_planet_board.' It also explains the behavior with and without dates.

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

A4.4/5.0
Disambiguation5/5

Each tool targets a distinct observational need: dark windows, eclipses, geocoding, moon state, phase calendar, planet overview, planet events, precise positions, rise/set times, broad snapshot, and solar day. Cross-references among descriptions prevent ambiguity despite overlapping data like rise/set times appearing in several tools.

Naming Consistency4/5

All tools share the astro_ prefix and use snake_case, creating a predictable pattern. The naming is mostly noun-based (the object of interest), but astro_find_place and astro_rise_set break the pure-noun pattern, introducing a slight inconsistency.

Tool Count5/5

With 11 tools, the server covers the major areas of practical astronomy without redundancy. Each tool provides a distinct calculation or data set, and the count fits the expected scope for an astronomy API.

Completeness4/5

The tool set covers solar, lunar, planetary, eclipse, positional, and visibility needs comprehensively. However, there is no explicit tool for equinoxes and solstices, which would be a natural inclusion for a cycle-focused astronomy server, creating a minor gap.

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