Menstrual Cycle Prediction for AI Agents

Overview

Provides current cycle status, PMS timing, and comprehensive period tracking information, perfect for women's health apps and cycle monitoring applications.

Live Test Menstrual Cycle Prediction for AI Agents Source →

The tool

Once your client is connected to the VerveContext server, this appears in its tool list as MenstrualCyclePredictionforAIAgents. 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": "MenstrualCyclePredictionforAIAgents",
  "arguments": {
    "last_period": "2024-01-01"
  }
}

You do not name the tool yourself; the model picks it. Asking about 2024-01-01 in the terms this source covers is enough for it to reach for MenstrualCyclePredictionforAIAgents 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
`cycle_length`Optional	integer	Average cycle length in days default 28 · range 21–35
`period_length`Optional	integer	Average period duration in days default 5 · range 2–10
`cycles`Optional	integer	Number of future cycles to calculate default 3 · range 1–12

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": {
    "last_period_date": "2024-01-01",
    "cycle_length": 28,
    "period_length": 5,
    "cycles_calculated": 3,
    "cycles": [
      {
        "cycle_number": 1,
        "period": {
          "start_date": "2024-01-01",
          "end_date": "2024-01-05",
          "duration_days": 5
        },
        "ovulation": {
          "date": "2024-01-15",
          "day_of_cycle": 14
        },
        "fertile_window": {
          "start_date": "2024-01-10",
          "end_date": "2024-01-15",
          "duration_days": 6
        },
        "pms_phase": {
          "start_date": "2023-12-21",
          "end_date": "2023-12-31"
        },
        "cycle_phases": {
          "menstrual": {
            "start": "2024-01-01",
            "end": "2024-01-05",
            "description": "Menstruation"
          },
          "follicular": {
            "start": "2024-01-06",
            "end": "2024-01-14",
            "description": "Follicular phase - preparing for ovulation"
          },
          "ovulation": {
            "date": "2024-01-15",
            "description": "Ovulation - most fertile day"
          },
          "luteal": {
            "start": "2024-01-16",
            "end": "2024-01-28",
            "description": "Luteal phase - preparing for next period"
          }
        },
        "status": "past",
        "days_until": null,
        "days_ago": 715
      },
      {
        "cycle_number": 2,
        "period": {
          "start_date": "2024-01-29",
          "end_date": "2024-02-02",
          "duration_days": 5
        },
        "ovulation": {
          "date": "2024-02-12",
          "day_of_cycle": 14
        },
        "fertile_window": {
          "start_date": "2024-02-07",
          "end_date": "2024-02-12",
          "duration_days": 6
        },
        "pms_phase": {
          "start_date": "2024-01-18",
          "end_date": "2024-01-28"
        },
        "cycle_phases": {
          "menstrual": {
            "start": "2024-01-29",
            "end": "2024-02-02",
            "description": "Menstruation"
          },
          "follicular": {
            "start": "2024-02-03",
            "end": "2024-02-11",
            "description": "Follicular phase - preparing for ovulation"
          },
          "ovulation": {
            "date": "2024-02-12",
            "description": "Ovulation - most fertile day"
          },
          "luteal": {
            "start": "2024-02-13",
            "end": "2024-02-25",
            "description": "Luteal phase - preparing for next period"
          }
        },
        "status": "past",
        "days_until": null,
        "days_ago": 687
      },
      {
        "cycle_number": 3,
        "period": {
          "start_date": "2024-02-26",
          "end_date": "2024-03-01",
          "duration_days": 5
        },
        "ovulation": {
          "date": "2024-03-11",
          "day_of_cycle": 14
        },
        "fertile_window": {
          "start_date": "2024-03-06",
          "end_date": "2024-03-11",
          "duration_days": 6
        },
        "pms_phase": {
          "start_date": "2024-02-15",
          "end_date": "2024-02-25"
        },
        "cycle_phases": {
          "menstrual": {
            "start": "2024-02-26",
            "end": "2024-03-01",
            "description": "Menstruation"
          },
          "follicular": {
            "start": "2024-03-02",
            "end": "2024-03-10",
            "description": "Follicular phase - preparing for ovulation"
          },
          "ovulation": {
            "date": "2024-03-11",
            "description": "Ovulation - most fertile day"
          },
          "luteal": {
            "start": "2024-03-12",
            "end": "2024-03-24",
            "description": "Luteal phase - preparing for next period"
          }
        },
        "status": "past",
        "days_until": null,
        "days_ago": 659
      }
    ],
    "current_status": {
      "phase": "Unknown",
      "description": "",
      "next_period": null,
      "days_until_next_period": null
    },
    "averages": {
      "cycle_length": 28,
      "period_duration": 5,
      "days_between_periods": 28
    },
    "disclaimer": "This calculator provides estimates only. Actual cycles may vary. Consult a 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
`last_period_date`	string	`2024-01-01`	First day of last menstrual period
`cycle_length`	number	`28`	Average menstrual cycle length in days
`period_length`	number	`5`	Average menstrual period duration in days
`cycles_calculated`	number	`3`	Total number of cycles calculated
`cycles`	array[3]		Array of calculated menstrual cycles with details
`cycles.0.cycle_number`	number	`1`	Sequential number of the cycle
`cycles.0.period`	object	`{…}`	Start, end and length of the period for this cycle
`cycles.0.period.start_date`	string	`2024-01-01`	Start date of menstrual period
`cycles.0.period.end_date`	string	`2024-01-05`	End date of menstrual period
`cycles.0.period.duration_days`	number	`5`	Duration of period in days
`cycles.0.ovulation`	object	`{…}`	Estimated ovulation date and which day of the cycle it falls on
`cycles.0.ovulation.date`	string	`2024-01-15`	Predicted ovulation date in cycle
`cycles.0.ovulation.day_of_cycle`	number	`14`	Day of cycle when ovulation occurs
`cycles.0.fertile_window`	object	`{…}`	Range of days conception is possible in this cycle
`cycles.0.fertile_window.start_date`	string	`2024-01-10`	Start of fertile window for conception
`cycles.0.fertile_window.end_date`	string	`2024-01-15`	End of fertile window for conception
`cycles.0.fertile_window.duration_days`	number	`6`	Duration of fertile window in days
`cycles.0.pms_phase`	object	`{…}`	Range of days premenstrual symptoms are expected
`cycles.0.pms_phase.start_date`Premium	string	`2023-12-21`	Start date of PMS phase
`cycles.0.pms_phase.end_date`Premium	string	`2023-12-31`	End date of PMS phase
`cycles.0.cycle_phases`Premium	object	`{…}`	Detailed breakdown of menstrual cycle phases
`cycles.0.cycle_phases.menstrual`Premium	object	`{…}`	The bleeding phase, with its dates
`cycles.0.cycle_phases.menstrual.start`Premium	string	`2024-01-01`	Start date of menstrual phase
`cycles.0.cycle_phases.menstrual.end`Premium	string	`2024-01-05`	End date of menstrual phase
`cycles.0.cycle_phases.menstrual.description`Premium	string	`Menstruation`	Description of menstrual phase
`cycles.0.cycle_phases.follicular`Premium	object	`{…}`	From the end of the period to ovulation
`cycles.0.cycle_phases.follicular.start`Premium	string	`2024-01-06`	Start date of follicular phase
`cycles.0.cycle_phases.follicular.end`Premium	string	`2024-01-14`	End date of follicular phase
`cycles.0.cycle_phases.follicular.description`Premium	string	`Follicular phase - preparing for ovulation`	Description of follicular phase
`cycles.0.cycle_phases.ovulation`Premium	object	`{…}`	The day the egg is released
`cycles.0.cycle_phases.ovulation.date`Premium	string	`2024-01-15`	Ovulation date within cycle
`cycles.0.cycle_phases.ovulation.description`Premium	string	`Ovulation - most fertile day`	Description of ovulation phase
`cycles.0.cycle_phases.luteal`Premium	object	`{…}`	From ovulation to the start of the next period
`cycles.0.cycle_phases.luteal.start`Premium	string	`2024-01-16`	Start date of luteal phase
`cycles.0.cycle_phases.luteal.end`Premium	string	`2024-01-28`	End date of luteal phase
`cycles.0.cycle_phases.luteal.description`Premium	string	`Luteal phase - preparing for next period`	Description of luteal phase
`cycles.0.status`Premium	string	`past`	Status of cycle relative to current date
`cycles.0.days_until`Premium	object	`null`	Days until cycle phase occurs
`cycles.0.days_ago`Premium	number	`715`	Days since cycle phase occurred
`current_status`	object	`{…}`	Which phase today falls in and when the next period is due
`current_status.phase`Premium	string	`Unknown`	Current menstrual cycle phase name
`current_status.description`Premium	string		Description of current cycle phase
`current_status.next_period`Premium	object	`null`	Date of next expected menstrual period
`current_status.days_until_next_period`Premium	object	`null`	Days until next menstrual period starts
`averages`	object	`{…}`	Average cycle length, period duration and gap between periods
`averages.cycle_length`Premium	number	`28`	Average menstrual cycle length across periods
`averages.period_duration`Premium	number	`5`	Average menstrual period duration across cycles
`averages.days_between_periods`Premium	number	`28`	Average days between menstrual period starts
`disclaimer`	string	`This calculator provides estimates only. Actual cycles may vary. Consult a healthcare provider for medical advice.`	Legal disclaimer about calculation accuracy

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

Use cases

Period Tracking: Build period tracking applications with accurate cycle predictions, period start dates, and phase identification
Cycle Prediction: Predict future menstrual cycles with customizable cycle length and period duration for planning and preparation
Health Monitoring: Create women's health monitoring tools with detailed cycle phase information including follicular, ovulation, and luteal phases
Health Insights: Provide cycle-based health insights and symptom tracking aligned with menstrual phases for better health awareness

Other ways to use Menstrual Cycle Prediction for AI Agents

Set up Menstrual Cycle Prediction 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 →