Due Date Calculation for AI Agents

Overview

Includes pregnancy milestones, percentage completion, and important dates like trimester transitions, perfect for pregnancy tracking and prenatal care applications.

The tool

Once your client is connected to the VerveContext server, this appears in its tool list as DueDateCalculationforAIAgents. 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": "DueDateCalculationforAIAgents",
  "arguments": {
    "last_period": "2025-06-01"
  }
}

You do not name the tool yourself; the model picks it. Asking about 2025-06-01 in the terms this source covers is enough for it to reach for DueDateCalculationforAIAgents 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.

Argument	Type	Description
`last_period`Required	string	First day of last menstrual period (YYYY-MM-DD) 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": {
    "calculation_method": "last_period",
    "last_period_date": "2024-01-01",
    "estimated_conception_date": "2024-01-15",
    "due_date": "2024-10-07",
    "current_progress": {
      "days_pregnant": 715,
      "weeks_pregnant": 102,
      "days_into_week": 1,
      "formatted": "102 weeks, 1 days",
      "trimester": 3,
      "percentage_complete": 255.36
    },
    "time_until_due": {
      "days": 0,
      "weeks": 0,
      "days_extra": 0,
      "formatted": "Past due date",
      "is_overdue": true
    },
    "upcoming_milestones": [],
    "important_dates": {
      "end_first_trimester": "2024-04-01",
      "end_second_trimester": "2024-07-08",
      "full_term_begins": "2024-09-16"
    },
    "disclaimer": "This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice."
  }
}

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
`calculation_method`	string	`last_period`	Method used for calculation: last_period or conception_date
`last_period_date`Premium	string	`2024-01-01`	Estimated first day of last menstrual period
`estimated_conception_date`Premium	string	`2024-01-15`	Conception date provided as input
`due_date`	string	`2024-10-07`	Estimated delivery date in ISO format
`current_progress`	object	`{…}`	How far along the pregnancy is today, in days and weeks
`current_progress.days_pregnant`Premium	number	`715`	Total number of days pregnant
`current_progress.weeks_pregnant`Premium	number	`102`	Number of complete weeks of pregnancy
`current_progress.days_into_week`Premium	number	`1`	Additional days beyond complete weeks
`current_progress.formatted`Premium	string	`102 weeks, 1 days`	Human-readable pregnancy duration with weeks and days
`current_progress.trimester`Premium	number	`3`	Current trimester number: 1, 2, or 3
`current_progress.percentage_complete`Premium	number	`255.36`	Pregnancy completion percentage relative to due date
`time_until_due`	object	`{…}`	How long until the due date, with a formatted summary
`time_until_due.days`Premium	number	`0`	Complete days remaining until due date
`time_until_due.weeks`Premium	number	`0`	Complete weeks remaining until due date
`time_until_due.days_extra`Premium	number	`0`	Additional days beyond complete weeks remaining
`time_until_due.formatted`Premium	string	`Past due date`	Human-readable time remaining until delivery
`time_until_due.is_overdue`Premium	boolean	`true`	Whether pregnancy has passed the due date
`upcoming_milestones`Premium	array	`[]`	Array of upcoming pregnancy milestones and dates
`important_dates`	object	`{…}`	Key milestones: the end of each trimester and viability
`important_dates.end_first_trimester`Premium	string	`2024-04-01`	Estimated end date of first trimester
`important_dates.end_second_trimester`Premium	string	`2024-07-08`	Estimated end date of second trimester
`important_dates.full_term_begins`Premium	string	`2024-09-16`	Date when pregnancy reaches full term status
`disclaimer`	string	`This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice.`	Medical disclaimer about estimated due dates

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 calculation_method: 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.

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 source is not part of VerveContext. Check the catalog.
`429`	Out of credits, or a brief rate limit. The message tells them apart.

A call costs 1 credit each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.

Use cases

Pregnancy Tracking: Build pregnancy tracking applications with accurate due date calculations based on last menstrual period or conception date
Prenatal Care: Calculate gestational age for prenatal care appointments, monitoring fetal development, and scheduling medical tests
Maternity Planning: Create maternity planning tools with delivery date estimates, trimester breakdowns, and important date tracking
Milestone Tracking: Provide pregnancy milestone information with week-by-week pregnancy timeline and key development stages

Other ways to use Due Date Calculation for AI Agents

Set up Due Date Calculation 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 →

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