mcp-stargazing

get_moon_info

Retrieve lunar phase, illumination, and position; add observer coordinates to get local altitude, azimuth, moonrise, and moonset times.

Instructions

Get detailed information about the Moon's phase and position.

Use when: you need lunar phase or illumination facts, with optional observer-local events. Do not use when: you need to rank observing sites or assess a target's overall suitability. Requires: time and timezone; supply both lat and lon for local position and rise/set. Follow-up: get_telescope_targets for equipment-aware targets; plan_stargazing_session for the combined effect of moonlight, weather, place, and observing goals.

When lat and lon are provided, also returns the Moon's local altitude, azimuth, moonrise, and moonset relative to the observer.

Args: time: Date string "YYYY-MM-DD HH:MM:SS" time_zone: IANA timezone string lat: Observer latitude in degrees (optional, for local position) lon: Observer longitude in degrees (optional, for local position)

Returns: Dict with keys "data", "_meta". "data" contains illumination, phase_name, age_days, elongation, earth_distance, and optionally altitude/azimuth plus moonrise/moonset (UTC unix timestamps).

Input Schema

Name	Required	Description	Default
`lat`	No
`lon`	No
`time`	Yes
`time_zone`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.0.1Jul 4, 2026

addedInput schema / properties / lat

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null
+}

addedInput schema / properties / lon

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null
+}

First observedv1.0.0Jan 4, 2026

TDQS

A4.7/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does disclose the key conditional behavior: lat/lon are optional, and supplying both unlocks local altitude, azimuth, moonrise, and moonset. It does not cover failure modes such as invalid timezone strings or out-of-range coordinates, which would be needed for a 5.

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 'Use when / Do not use when / Requires / Follow-up' block is front-loaded and dense with actionable content. However, the Args and Returns sections largely restate the input schema and output schema, so some of the closing text does not earn its place.

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 four-parameter read tool with an output schema, the description covers inputs, conditional local-position behavior, exclusions, and next steps. Nothing an agent needs to invoke it correctly is missing.

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%, and the description fully compensates: it gives the exact time format "YYYY-MM-DD HH:MM:SS", specifies an IANA timezone string, marks lat/lon as optional degrees and states the condition under which they matter. Every parameter is documented with more precision than a 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?

States a specific verb and resource (Moon phase and position) and immediately scopes what it covers: illumination, phase, and observer-local position. It explicitly distinguishes itself from siblings that rank sites or assess target suitability, so an agent can choose it without opening other schemas.

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?

Provides an explicit 'Use when' and 'Do not use when' pair, names the prerequisites (time, timezone, both lat and lon for local results), and routes follow-ups to get_telescope_targets and plan_stargazing_session. Alternatives and exclusions are both spelled out.

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