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IBM

chuk-mcp-celestial

by IBM

get_sun_moon_data

Retrieve sun and moon rise/set times, moon phase, and illumination data for any location and date to plan outdoor activities, photography, or astronomical observations.

Instructions

Get complete sun and moon data for one day at a specific location.

Provides rise, set, and transit times for the sun and moon, twilight times, moon phase, and illumination percentage. Essential for planning outdoor activities, photography, navigation, and astronomical observations.

Args: date: Date in YYYY-MM-DD format. No leading zeros required. latitude: Latitude in decimal degrees. Range: -90 to 90 (negative = South, positive = North) longitude: Longitude in decimal degrees. Range: -180 to 180 (negative = West, positive = East) timezone: Timezone offset from UTC in hours (e.g., -8 for PST, 1 for CET). Positive = East of UTC, Negative = West of UTC. If not provided, UTC (0) is used. dst: Whether to apply daylight saving time adjustment. If not provided, defaults to false. label: Optional user label (max 20 characters) to identify this query in the response

Returns: OneDayResponse: GeoJSON Feature containing: - geometry: Location coordinates - properties.data: Complete sun and moon information: - sundata: List of sun events (rise, set, transit, civil twilight begin/end) - moondata: List of moon events (rise, set, transit) - curphase: Current moon phase description - fracillum: Percentage of moon illuminated (e.g., "92%") - closestphase: Details of the nearest moon phase

Tips for LLMs: - Times are in the requested timezone (or UTC if not specified) - sundata and moondata may be empty in polar regions during extreme seasons - Civil twilight is when the sun is 6 degrees below horizon - Use fracillum to determine moon brightness for night photography or stargazing - Moon transit time indicates when moon is highest in the sky (best viewing)

Example: data = await get_sun_moon_data( date="2005-9-20", latitude=47.60, longitude=-122.33, timezone=-8, dst=True ) sunrise = next(e for e in data.properties.data.sundata if e.phen == "Rise") print(f"Sunrise at {sunrise.time}")

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
dateYes
latitudeYes
longitudeYes
timezoneNo
dstNo
labelNo
Behavior4/5

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: timezone handling, polar region edge cases (empty data), twilight definition, and practical applications. It doesn't mention rate limits, authentication needs, or error conditions, but provides substantial operational context.

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?

Well-structured with purpose statement, usage context, parameter details, return format, LLM tips, and example. Some redundancy exists (e.g., timezone sign explained twice), but overall efficient with each section serving a clear purpose. Could be slightly more 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 6-parameter tool with no annotations and no output schema, the description provides comprehensive coverage: clear purpose, parameter semantics, return format details (GeoJSON structure with specific data fields), edge cases, and practical usage tips. It fully compensates for the lack of structured metadata.

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

Parameters5/5

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

With 0% schema description coverage, the description fully compensates by providing detailed parameter documentation: format requirements (YYYY-MM-DD), ranges (-90 to 90, -180 to 180), sign conventions (negative=South/West), defaults (timezone=UTC, dst=false), and optionality. It adds significant value beyond the bare 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 clearly states the tool 'Get complete sun and moon data for one day at a specific location' with specific resources (sun and moon data) and scope (one day, specific location). It distinguishes from siblings by focusing on daily sun/moon events rather than seasons, phases, planets, or eclipses.

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 context for when to use this tool ('Essential for planning outdoor activities, photography, navigation, and astronomical observations'), but doesn't explicitly state when to choose sibling tools like get_moon_phases or get_planet_events instead. The guidance is helpful but lacks explicit alternatives.

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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