mcp-stargazing

get_celestial_pos

Calculate a celestial object's altitude and azimuth for a given location, time, and timezone to determine its sky position.

Instructions

Calculate the altitude and azimuth angles of a celestial object.

Use when: you need one named object's position at a specified place and instant. Do not use when: you need an all-night target list or a complete observing decision. Requires: object name, observer coordinates, observation time, and its IANA timezone. Follow-up: get_celestial_rise_set for events; get_nightly_forecast for night targets; plan_stargazing_session for a complete observing decision.

Args: celestial_object: Name of object (e.g. "sun", "moon", "andromeda") lon: Observer longitude in degrees lat: Observer latitude in degrees time: Observation time string "YYYY-MM-DD HH:MM:SS" time_zone: IANA timezone string

Returns: Dict with keys "data", "_meta". "data" contains "altitude" and "azimuth" (degrees).

Input Schema

Name	Required	Description	Default
`lat`	Yes
`lon`	Yes
`time`	Yes
`time_zone`	Yes
`celestial_object`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jan 4, 2026

TDQS

A4.8/5.0

Behavior4/5

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

No annotations are provided, so the description carries the disclosure burden and does a good job stating required inputs, time format, timezone requirements, and the returned data structure. It could be slightly stronger by explicitly noting that this is a pure calculation with no side effects, but the behavior is otherwise clear.

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?

The description is well structured and front-loaded: purpose first, then usage boundaries, requirements, follow-ups, arguments, and return shape. The sections are compact and each adds useful information without waste.

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?

Given the tool's complexity, five required parameters, lack of annotations, and available output schema, the description is complete. It covers purpose, usage boundaries, all parameter meanings, and the return structure sufficiently for an agent to invoke it correctly.

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?

Schema description coverage is 0%, so the description must compensate for all five required parameters. It documents each one, including examples for celestial_object, units for lon/lat, the exact time string format, and that time_zone is an IANA timezone.

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 uses a specific verb-resource pair: calculate altitude and azimuth angles for a celestial object. It clearly distinguishes the tool from siblings by saying it returns one named object's position rather than a list, events, forecast, or full observing plan.

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?

It explicitly states when to use the tool, when not to use it, and which alternative sibling tools to use for rise/set events, nightly targets, and complete observing decisions. The guidance is concrete and actionable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.