Docs/Sources/Julian Day Conversion for AI Agents

Julian Day Conversion for AI Agents

Convert Between Gregorian and Julian Day

OperationalCredits 2 per callp50 186msScience

Overview

Perfect for astronomical calculations, historical date research, and applications that need a continuous day count across calendar systems.

Live Test Julian Day Conversion for AI Agents Source →

The tool

Once your client is connected to the VerveContext server, this appears in its tool list as JulianDayConversionforAIAgents. 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": "JulianDayConversionforAIAgents",
  "arguments": {
    "date": "2024-03-15"
  }
}

You do not name the tool yourself; the model picks it. Asking about 2024-03-15 in the terms this source covers is enough for it to reach for JulianDayConversionforAIAgents on its own — naming it explicitly also works, and is the way to force the call.

Connecting

One server URL covers every source 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": {
    "vervecontext": {
      "url": "https://api.vervecontext.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.

ArgumentTypeDescription
dateRequiredstringThe Gregorian date in YYYY-MM-DD format
date

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": {
    "gregorian": "2024-03-15",
    "julianDayNumber": 2460385,
    "modifiedJulianDate": 60384.5,
    "dayOfWeek": "Friday",
    "weekNumber": 11,
    "dayOfYear": 75,
    "daysFromToday": -340
  }
}

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.

FieldTypeExampleDescription
gregorianstring2024-03-15The equivalent Gregorian calendar date
julianDayNumbernumber2460385Days elapsed since noon on 1 January 4713 BC
modifiedJulianDatenumber60384.5Julian day number shifted to start at midnight on 17 November 1858
dayOfWeekstringFridayDay of the week the date falls on
weekNumbernumber11ISO week number (1-53)
dayOfYearnumber75Day of the year (1-366)
daysFromTodayPremiumnumber-340Number of days from today (negative = past, positive = future)

Why ground on it

A model can produce something that looks like this answer from its training data, and be confidently out of date or simply wrong. This source returns the current value in a shape you can check, which is the difference between an answer you can cite and one you have to hedge.

Point an evaluation at gregorian: it is the field most worth pinning a claim to, and it is either present and current or absent — never plausibly invented.

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.

StatusWhat it means
400 / 422The arguments did not validate. The message names the offending one.
401The OAuth session is invalid or expired — reconnect the server.
403Blocked by a key restriction or an IP allow-list. Never a bad identity.
404This source is not part of VerveContext. Check the catalog.
429Out 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

Astronomical Software
Calculate precise day numbers for celestial events
Historical Research
Convert historical dates to a unified day count
Date Arithmetic
Calculate day differences across long time spans
Scientific Applications
Use continuous day counts for time series data

Other ways to use Julian Day Conversion for AI Agents

Set up Julian Day Conversion for AI Agents on VerveContext, or reach the same source a different way. Your VerveContext 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 →
Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKit →Reference →
Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheets →Reference →

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