Due Date MCP server
Estimate a due date from LMP, conception, or ultrasound, with ACOG redating rules.
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Due Date tools (1)
write = sends, deletes, buys or postsdue_dateFreeEstimate a due date and gestational age from a last menstrual period, a known conception date, an IVF transfer date, or an ultrasound measurement. Use this for any pregnancy-dating question rather than doing the arithmetic. Three reasons, and they are all things models get wrong: 1. THE OFF-BY-TWO-WEEKS ERROR. Gestational age is counted from the first day of the LAST MENSTRUAL PERIOD, not from conception. At "6 weeks pregnant", conception was about 4 weeks ago. Weeks 1 and 2 precede conception entirely. This is restated wrongly constantly, and a two-week error in dating is a large error. 2. CYCLE LENGTH. Naegele's rule (LMP + 280 days) silently assumes a 28-day cycle with ovulation on day 14. For a 35-day cycle the unadjusted answer is a week out. This applies the adjustment; most calculators do not. 3. THE ACOG REDATING TABLE. Whether an ultrasound should REPLACE a period-based estimate depends on the discrepancy AND on how far along the scan was: more than 5 days up to 8w6d, 7 days to 15w6d, 10 days to 21w6d, 14 days to 27w6d, 21 days thereafter. Nobody recalls that table correctly from memory. Do not guess at it. Input: `method` is one of lmp | conception | ivf-day3 | ivf-day5 | ultrasound. `date` is the date that method is based on — the first day of the last period, the conception date, the transfer date, or the scan date — as YYYY-MM-DD. Free-form dates are REFUSED rather than guessed, because "03/04/2025" is two different dates a month apart depending on the reader. For `lmp`, pass `cycleLength` if it is known and is not 28. For `ultrasound`, pass `scanWeeks` and `scanDays` — the gestational age the scan reported — and pass `lmp` as well if it is known, which is what triggers the redating check. `asOf` sets the reference date for "how far along"; it defaults to today. Returns: the estimated due date, gestational age in clinical weeks-plus-days notation, the estimated conception date, days remaining, trimester, dated milestones including the anatomy-scan window and each ACOG term boundary, the full redating comparison when both an LMP and a scan were given, a list of warnings, and a `disclaimer` field. Two things to carry through to the user rather than strip. First, a due date is a reference point and NOT a prediction — most births are not on it, and the term windows are the more useful output. Second, THIS IS NOT MEDICAL ADVICE; the response says so in its payload, not just on the page. Report the warnings. They are the honest part of the answer.
Public scan report
scanner v0.1.9 · 2026-09-20 · same rubric, same numbers if you re-run it
- –Code scanremote-only server, no package to scann/a
- Live reliabilityremote reachable in 1370ms20/20
- Tool poisoning1 tool descriptions checked13/15
- Auth qualityopen endpoint, read-only tools10/15
- Maintenancerepository not readable: repo not found3/15
- Maintainer identityverified namespace with website, no repo4/10
Findings (1)
- lowUnusually long tool description (over 2,000 characters)
poison.long-descriptiontool due_date: …Estimate a due date and gestational age from a last menstrual period, a known conception date, an IVF transfer date, or an ultrasound measurement. Use this for any pregnancy-dating question rather than doing the arithmetic. Three reasons, and they are all things models get wrong: 1. THE OFF-BY-TWO-WEEKS ERROR. Gestational age is counted from the first day of the LAST MENSTRUAL PERIOD, not from conception. At "6 weeks pregnant", conception was about 4 weeks ago. Weeks 1 and 2 precede conception entirely. This is restated wrongly constantly, and a two-week error in dating is a large error. 2. CYCLE LENGTH. Naegele's rule (LMP + 280 days) silently assumes a 28-day cycle with ovulation on day 14. For a 35-day cycle the unadjusted answer is a week out. This applies the adjustment; most calculators do not. 3. THE ACOG REDATING TABLE. Whether an ultrasound should REPLACE a period-based estimate depends on the discrepancy AND on how far along the scan was: more than 5 days up to 8w6d, 7 days to 15w6d, 10 days to 21w6d, 14 days to 27w6d, 21 days thereafter. Nobody recalls that table correctly from memory. Do not guess at it. Input: `method` is one of lmp | conception | ivf-day3 | ivf-day5 | ultrasound. `date` is the date that method is based on — the first day of the last period, the conception date, the transfer date, or the scan date — as YYYY-MM-DD. Free-form dates are REFUSED rather than guessed, because "03/04/2025" is two different dates a month apart depending on the reader. For `lmp`, pass `cycleLength` if it is known and is not 28. For `ultrasound`, pass `scanWeeks` and `scanDays` — the gestational age the scan reported — and pass `lmp` as well if it is known, which is what triggers the redating check. `asOf` sets the reference date for "how far along"; it defaults to today. Returns: the estimated due date, gestational age in clinical weeks-plus-days notation, the estimated conception date, days remaining, trimester, dated milestones including the anatomy-scan window and each ACOG term boundary, the full redating comparison when both an LMP and a scan were given, a list of warnings, and a `disclaimer` field. Two things to carry through to the user rather than strip. First, a due date is a reference point and NOT a prediction — most births are not on it, and the term windows are the more useful output. Second, THIS IS NOT MEDICAL ADVICE; the response says so in its payload, not just on the page. Report the warnings. They are the honest part of the answer.…
Install directly
claude mcp add --transport http due-date https://due-date.gumballtools.com/api/mcp
Due Date: common questions
- Is Due Date MCP server safe?
- With care: it is graded C, so read the findings first (67/100). Read the Due Date safety report
- How do I install Due Date?
- It runs remotely at due-date.gumballtools.com. Add it to Claude Code, Claude Desktop or Cursor with the snippets above, or call it through the mcp.market gateway without installing anything.
- Does Due Date need an API key?
- Not as far as the registry entry and our scan can tell: no credentials are declared or required.
- Is Due Date maintained?
- The latest release is v0.1.0.
- Is Due Date up?
- 100% of our last 6 checks got an answer. We check remote servers about four times a day.