Moon Phase Software

Moon sign

get_moon_sign

Read-onlyIdempotent

Returns the zodiac sign the Moon is in at a date and local time, in a time zone or city, with its degree in the sign and the next sign change. Without a time it returns every sign the Moon is in during that date. The tropical or the Lahiri sidereal zodiac can be chosen.

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_sign"
  }
}

Input Schema

Name	Required	Description
`date`	No	Local calendar date as YYYY-MM-DD, from 1900 to 2100, such as a birth date; the Moon right now when omitted.
`time`	No	Local clock time as HH:MM on a 24-hour clock, such as a birth time. Without it the result covers the whole date.
`place`	No	A city from the website's list of 136 world cities, such as the birthplace; its time zone is used unless timeZone is given.
`zodiac`	No	Zodiac origin: tropical (the March equinox) or lahiri (sidereal); tropical when omitted.
`timeZone`	No	IANA time zone name of the date and time, such as the birthplace's zone; 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

A3.7/5.0

Behavior3/5

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

Annotations already cover readOnly, idempotent, non-destructive, and openWorldHint=false, so the safety profile is fully declared. The description adds real behavior beyond that: the default is the current moment when date is omitted, and a date-only call returns a sign set rather than a single sign. It says nothing about output shape, but an output schema exists to carry that.

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 tight sentences with the main behavior front-loaded and the fallback and zodiac option following in logical order. No filler, no restatement of the title.

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?

With an output schema covering return values, full parameter documentation, and rich annotations, nothing material is left for the description to carry. The description still covers the optional-argument behavior, which is the one thing the schema does not spell out.

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 coverage is 100%, so every parameter already carries a substantive description including defaults, formats, and precedence between place and timeZone. The description restates the place/timeZone and tropical/lahiri choices without adding syntax or edge-case meaning, so the baseline 3 is correct.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Names a precise verb ('Returns') and a specific resource ('the zodiac sign the Moon is in at a date and local time'), plus the exact output content (degree in sign, next sign change). An agent can tell this is not a phase, distance, or calendar tool. It stops short of explicitly differentiating from the sibling tools, so a 4 rather than a 5.

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?

The seasonal conditional ('Without a time it returns every sign the Moon is in during that date') implicitly tells the caller when to supply a time versus not, and 'the tropical or the Lahiri sidereal zodiac can be chosen' hints at a choice. There is no explicit when-to-use/when-not or routing to a sibling.

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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