genealogy-mcp

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convert_calendar

Read-only

Convert historical dates between Julian, Gregorian, Hebrew, and French Republican calendars for genealogy records, accounting for regional date shifts over time.

Instructions

Convert between calendars of old records: Julian (old style; Russia until February 1918: +10 days in the 1600s, +11 in the 1700s, +12 in the 1800s, +13 in 1900–1918), Gregorian, Hebrew (Jewish registers, tombstones) and the French Republican calendar (1792–1805).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "date": "<date>"
    },
    "name": "convert_calendar"
  }
}

Input Schema

Name	Required	Description	Default
`to`	No		gregorian
`date`	Yes	'1899-10-09' / '9.10.1899' (Julian or Gregorian), '15 Nisan 5650' (Hebrew), '18 Brumaire an VIII' (French Republican)
`from_calendar`	No	The calendar of `date`; auto: Hebrew and Republican are recognised by month names, a plain date is Julian when converting to Gregorian and vice versa	auto

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.5.1Oct 16, 2026

TDQS

A3.5/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description contributes real domain behavior (the century-dependent Julian drift: +10 in 1600s through +13 in 1900–1918), which is useful context beyond the annotations, but it says nothing about error handling, ambiguous-input resolution, or out-of-range dates.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single dense sentence that front-loads the core action and then parenthetically supplies the historical windows; every clause carries information. It is slightly over-packed but no sentence is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value documentation is not needed, and annotations cover the read-only/no-network profile. For a three-parameter read-only conversion tool, the description supplies enough domain framing, with only ambiguity/error behavior left unspecified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 67%, and the schema itself already documents the date string formats and explains that 'auto' recognizes Hebrew/Republican by month names. The description reinforces the calendar set and historical windows but adds little syntax or semantic detail for 'to' or 'from_calendar' beyond what the schema states.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (convert) and resource (calendars) and enumerates exactly which calendars are supported, which is concrete and unambiguous. It does not, however, differentiate itself from siblings like normalize_date or feast_date, so the agent gets the 'what' but not the 'why not that one'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied through domain context ('old records', the Julian windows before 1918 and Republican 1792–1805), which hints at genealogical date scenarios. There is no explicit when-to-use-vs-alternatives guidance relative to normalize_date or feast_date, so an agent must infer the boundary itself.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.