Moon Phase Skill

Overview

A moon phase and lunar phase API. Moon Phases works by calculating the moon phase based on the date provided. It returns the moon phase in a structured format.

Live Test Moon Phase Skill Skill →

The tool

Once your client is connected to the VerveKit server, this appears in its tool list as MoonPhaseSkill. It is read-only and open-world — it fetches and never mutates anything on your side — so most clients call it without asking you to confirm.

Tool call

{
  "name": "MoonPhaseSkill",
  "arguments": {}
}

Connecting

One server URL covers every skill in the catalog, including this one. Authorization is OAuth: the client opens a browser once, and there is no key to paste into a config file.

{
  "mcpServers": {
    "vervekit": {
      "url": "https://api.vervekit.com/v1/mcp"
    }
  }
}

Per-client setup — Claude, Cursor, VS Code, ChatGPT — is on the MCP setup page.

Arguments

These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made. Premium arguments are accepted on every plan but only take effect on plans that include them.

Argument	Type	Description
`today`Optional	boolean	Get the moon phase for today default true

What the model gets back

The result carries a structuredContent object matching the tool's declared outputSchema, so a client reads fields without parsing prose. status is "ok" and error is null on success; a null field means the value was not available for that input, not that the call failed.

Result

{
  "status": "ok",
  "error": null,
  "data": {
    "phase": "Waning Crescent",
    "phaseEmoji": "🌘",
    "illumination": 9.9,
    "waxing": false,
    "waning": true,
    "lunarAge": 26.61193415670738,
    "lunarAgePercent": 0.9011650706672754,
    "lunationNumber": 1274,
    "lunarDistance": 63.77810628163608,
    "nextFullMoon": "2026-01-16T00:00:00Z",
    "lastFullMoon": "2025-11-17T00:00:00Z",
    "daysToFullMoon": 28,
    "daysSinceFullMoon": 2
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`phase`	string	`Waning Crescent`	Current moon phase name
`phaseEmoji`	string	`🌘`	Emoji showing the current phase
`illumination`	number	`9.9`	Approximate illumination percentage (0-100)
`waxing`	boolean	`false`	Whether the illuminated fraction is growing
`waning`	boolean	`true`	Whether the illuminated fraction is shrinking
`lunarAge`	number	`26.61193415670738`	Days since the last new moon
`lunarAgePercent`	number	`0.9011650706672754`	How far through the lunar cycle the moon is, from 0 to 1
`lunationNumber`	number	`1274`	Which lunar cycle this is, counting from the new moon of January 1923
`lunarDistance`	number	`63.77810628163608`	Distance to the moon in Earth radii
`nextFullMoon`Premium	string	`2026-01-16T00:00:00Z`	Date of next full moon
`lastFullMoon`Premium	string	`2025-11-17T00:00:00Z`	Date of last full moon
`daysToFullMoon`Premium	number	`28`	Days until next full moon
`daysSinceFullMoon`Premium	number	`2`	Days since last full moon

Failure modes

Errors come back as tool errors carrying a sentence the model can act on, not a bare status code. Error handling covers the full list.

Status	What it means
`400` / `422`	The arguments did not validate. The message names the offending one.
`401`	The OAuth session is invalid or expired — reconnect the server.
`403`	Blocked by a key restriction or an IP allow-list. Never a bad identity.
`404`	This skill is not part of VerveKit. Check the catalog.
`429`	Out of credits, or a brief rate limit. The message tells them apart.

A call costs 2 credits each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.

Use cases

Night Sky Photography: Astrophotographers check lunar illumination and waxing status to schedule dark-sky Milky Way shoots around the new moon.
Biodynamic Planting Calendars: Gardening software aligns root and above-ground crop sowing schedules using lunar cycle progression and current lunar age.
Stargazing Event Planning: When planning evening telescope sessions, observatory guides inspect illumination percentages to schedule viewing nights under pitch-black skies.
Fishing Forecast Dashboards: Forecast peak feeding activity by pairing lunation numbers and waxing indicators with local marine tables in fishing apps.

Other ways to use Moon Phase Skill

Set up Moon Phase Skill on VerveKit, or reach the same source a different way. Your VerveKit account and credits work on all of them — one key, one balance.

Call it as a REST APIOne HTTPS endpoint and an x-api-key header, with SDKs for Node, Python and .NET.APIVerve →Reference →

Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheets →Reference →

Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.VerveContext →Reference →