Moon Phase Software

Moon distance

get_moon_distance

Read-onlyIdempotent

Returns the Moon's distance from Earth in kilometres and miles at a date and time, its apparent width, the previous and next perigee and apogee, and the next full Moon's distance with whether that full Moon is a supermoon.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "get_moon_distance"
  }
}

Input Schema

Name	Required	Description
`date`	No	Local calendar date as YYYY-MM-DD, from 1900 to 2100. Without a date and a time the result describes the Moon right now; a date alone gives 12:00 local time.
`time`	No	Local clock time as HH:MM on a 24-hour clock.
`timeZone`	No	IANA time zone name such as America/New_York or Asia/Tokyo; UTC when omitted.

Output Schema

Name	Required	Description	Default
`item`	Yes
`view`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 11, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds meaningful behavioural context beyond that: the result set includes derived/extrapolated values (previous and next perigee/apogee, next full Moon) and a supermoon determination, which tells the agent the payload is richer than a single number and spans past, present and future events.

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?

A single dense sentence that is front-loaded with the core output (distance) before layering on secondary values. Every clause corresponds to an actual returned field, so nothing is wasted, though the enumeration is long enough that a slight structural break would improve scanning.

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 read-only, three-optional-parameter computation tool with a fully described schema, complete annotations and an output schema, nothing an agent needs is missing. Default behaviour and timezone handling are covered by the schema, and return contents are previewed in the description even though the output schema formalises them.

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%, and the schema itself documents the YYYY-MM-DD format, the 1900–2100 range, the 12:00 default for date-only, the HH:MM 24-hour format and the IANA time zone default of UTC. The description adds nothing about parameters, so this sits at the baseline for fully documented schemas.

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 opens with a specific verb ("Returns") and enumerates the exact resource contents: distance in kilometres and miles, apparent width, previous/next perigee and apogee, and the next full Moon's distance plus supermoon status. This is precise enough to separate it from siblings like get_moon_phase or get_moonrise_moonset without opening any schema.

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

Usage Guidelines3/5

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

Usage context is implied: it is the tool for lunar distance/geometry at a moment in time, while sibling names suggest phase, sign, rise/set and calendar concerns. However, the description never states when to prefer this over those siblings, nor any exclusions or prerequisites. The default-behaviour note (no date/time returns now) is parameter guidance rather than tool-selection guidance.

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

All Moon Phase Software tools Inspect

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