mcp-jp-paid-leave

# mcp-jp-paid-leave

[日本語版 README はこちら](README.ja.md)

An [MCP](https://modelcontextprotocol.io) (Model Context Protocol) server for calculating Japan's statutory
annual paid leave ("nenkyu") under the Labor Standards Act: entitlement grants, attendance-rate checks,
proportional grants for part-time workers, carryover/prescription, and the 5-day mandatory-use rule.
It lets MCP-capable clients such as Claude Desktop invoke these calculations directly.

No network access is used at runtime. All statutory rules are embedded as constants in the code.

## Core design principle

- **Every number and judgment this server returns is the statutory minimum under the Labor Standards Act.**
- Any company policy that grants more than the statutory minimum must be passed explicitly as an
  argument to `apply_company_policy`.
- **Every tool response includes a `basis` field:**
  - `"legal_minimum"`: the statutory minimum value
  - `"company_policy_applied"`: the value after applying a company policy (only from `apply_company_policy`)
- If a company policy value is below the statutory minimum, `apply_company_policy` automatically corrects
  it to the statutory minimum and returns a `warning`.
- **Resilience to legal amendments**: rules that are known to have changed as of a specific effective date
  (such as the standard grant-days table) are stored as "rule generations with an effective date," and the
  generation valid at the calculation-target date is selected automatically. Calculating for a past period
  still uses the rules that were in force at that time. Every tool response includes a `meta` field with
  the effective date and source URL of each rule actually used, the date the data was last verified
  (`dataVerifiedOn`), and a staleness warning when applicable. See
  [Versioning policy](#versioning-policy) and [Maintenance policy](#maintenance-policy) below.

## Disclaimer

- **This tool computes the statutory minimum under the Labor Standards Act. The accuracy of its output
  is not guaranteed.**
- If your work rules (shugyo kisoku) provide more favorable terms to employees, those always take
  precedence over this tool's output.
- **For any important labor/HR decision (including anything touching discipline, dismissal, or payroll),
  always confirm with a qualified professional (e.g., a licensed Shakai Hoken Roumushi / labor and social
  security attorney).**

## Tools (7 total)

| Tool | Description |
| --- | --- |
| `calculate_entitlement` | Computes the grant date and number of days for a given grant occurrence, from hire date and reference-date method |
| `check_attendance_rate` | Checks whether the 80% attendance-rate requirement is met, with a numerator/denominator breakdown |
| `list_grant_schedule` | Lists the grant schedule for a given number of years from the hire date |
| `proportional_entitlement` | Computes the proportional grant for part-time workers, based on weekly/annual scheduled working days |
| `calculate_carryover` | Computes carryover, forfeiture under the 2-year prescription period, and remaining balance |
| `check_mandatory_five_days` | Determines whether an employee is subject to the mandatory 5-day rule, and reports compliance status |
| `apply_company_policy` | Applies a company policy on top of the statutory minimum, correcting and warning if it falls short |

### 1. calculate_entitlement

Give the hire date (`hireDate`) and which grant occurrence to compute (`grantNumber`: 1 = the first grant
at 6 months of service, 2 = the second grant at 1 year 6 months, etc.).

- `referenceDateMethod`: `"individual"` (the statutory default — each employee's own basis date) or
  `"uniform"` (a company-wide unified basis date, i.e. "seiitsu-teki toriatsukai")
- `uniformBasisMonthDays`: required when `uniform` is used — an array of `"MM-DD"` candidate basis dates
  (e.g. `["04-01"]` or `["04-01","10-01"]`)
- `weeklyScheduledDays` / `annualScheduledDays` / `weeklyScheduledHours`: optional, for proportional
  grants (part-time workers)

For the `uniform` method, the server correctly computes the recurring chain: once the first front-loaded
basis date is found, every subsequent grant recurs on the same month/day each year. Any period shortened
by front-loading is returned as `shortenedPeriod`, with a note that this period must be treated as fully
attended for attendance-rate purposes (when calling `check_attendance_rate`, count it as ordinary worked
days in `actualWorkedDays` etc. rather than as absence — don't carve it out as unattended).

Returns an error if the **statutory basis date** (`statutoryBasisDate`, not the hire date) falls **before
2001-04-01**. The current grant-days table (introduced by Act No. 112 of 1998) took effect for most
purposes on 1999-04-01, but a transitional schedule with lower figures for certain tenure brackets applied
through 2001-03-31. This tool does not implement that transitional schedule, so 2001-04-01 (once the
transition was fully complete) is the verified floor (see [Versioning policy](#versioning-policy) and
[CHANGELOG.md](CHANGELOG.md)).

**This floor applies to each grant's own basis date, not to the hire date.** No matter how old the hire
date is, a specific grant computes fine as long as that grant's basis date is on or after 2001-04-01. For
example, for an employee hired in 1995, computing "the most recent grant as of 2026" (the 31st grant,
basis date 2025-10-01) succeeds. Only grants whose own basis date is before 2001-04-01 (e.g. that same
employee's 1st grant, basis date 1995-10-01) return an error.

### 2. check_attendance_rate

Checks the "80% of all working days" requirement for entitlement.

**Design principle**: deciding whether a given day belongs in the numerator or is excluded from the
denominator is exactly the value this tool should provide — and exactly where humans and AI callers are
most likely to get it wrong. So the caller does not classify anything. Instead, break the period down into
the following 11 day-count fields and pass them as-is (all required except `asOfDate` — if a category
doesn't apply, pass `0` explicitly; omitting a field is an error, not an assumed zero):

| Argument | Meaning |
| --- | --- |
| `scheduledWorkingDays` | Total scheduled working days for the period (days with a work obligation; excludes scheduled days off) |
| `actualWorkedDays` | Days actually worked |
| `paidLeaveTakenDays` | Days of annual paid leave taken |
| `workInjuryOrIllnessLeaveDays` | Days on leave for a work-related injury or illness |
| `maternityLeaveDays` | Days of maternity leave (Labor Standards Act Article 65) |
| `childcareOrFamilyCareLeaveDays` | Days of childcare or family-care leave |
| `employerCausedSuspensionDays` | Days suspended for reasons attributable to the employer (including employer-caused management/operational-obstacle suspension) |
| `lawfulLaborDisputeDays` | Days with no work provided due to a lawful strike/labor dispute |
| `forceMajeureSuspensionDays` | Days suspended due to force majeure |
| `workedOnScheduledDayOffDays` | Days worked on what was originally a scheduled day off — **not** included in `scheduledWorkingDays` |
| `otherAbsenceDays` | Ordinary absence not covered by any category above (unauthorized absence, personal illness, etc.) |

`scheduledWorkingDays` must equal the sum of the other 9 fields (everything except
`workedOnScheduledDayOffDays`). A mismatch is an error — the tool never guesses at a reconciling number.

Based on Labor Standards Act Article 39 paragraph 10 / Article 65, Directive Hakki No. 17 (Sept. 13, 1947),
and Directive Kihatsu 0710 No. 3 (July 10, 2013), the tool classifies each field into one of four
treatments internally:

- **Added to the numerator**: `actualWorkedDays`, `paidLeaveTakenDays`, `workInjuryOrIllnessLeaveDays`,
  `maternityLeaveDays`, `childcareOrFamilyCareLeaveDays`
- **Ordinary absence (stays in the denominator, not added to the numerator)**: `otherAbsenceDays`
- **Excluded from total working days (the denominator)**: `employerCausedSuspensionDays`,
  `lawfulLaborDisputeDays`, `forceMajeureSuspensionDays` (Kihatsu 0710 No. 3, Section 1-3)
- **Not counted at all (never a scheduled working day to begin with)**: `workedOnScheduledDayOffDays`
  (Kihatsu 0710 No. 3, Section 1-1)

The result's `breakdown.classification` always includes each field's day count, its resulting treatment,
and the specific legal basis (statute or directive) for that treatment.

### 3. list_grant_schedule

Same arguments as `calculate_entitlement`, plus `numberOfYears` (how many grant occurrences to list).

For long-tenured employees whose early grants have a basis date before the verified floor (2001-04-01),
the call as a whole no longer fails. Those specific grants are returned as `supported: false` placeholders
(no grant-days figure), while every other grant is computed normally with `supported: true`. Check the
`supported` field on each entry.

### 4. proportional_entitlement

Computes the proportional grant from weekly scheduled days (1–4) or annual scheduled days. Returns an
error if weekly scheduled hours are 30 or more, or weekly scheduled days are 5 or more (such workers use
the standard table instead).

### 5. calculate_carryover

- `grants`: array of grant records (`grantDate`, `grantedDays`)
- `usageRecords`: array of usage records (`date`, `days`)
- `asOfDate`: the date to evaluate as of

Each grant expires 2 years after its grant date (Labor Standards Act Article 115). Usage is consumed
against the **oldest grant first** (this is common practice, not an explicit statutory rule — follow your
work rules if they specify otherwise).

### 6. check_mandatory_five_days

For employees granted 10 or more days of annual paid leave, determines compliance with the employer's
obligation to have the employee use 5 days within 1 year of the grant date (Labor Standards Act Article
39, paragraphs 7–8). Days taken at the employee's own request, or via a planned-leave scheme, count
against the 5-day requiremen