tilwhen date engine

Measured conclusion: Deep-tested. L2 outcome: tools_ok.

Deterministic date arithmetic with auditable receipts: business days, due dates, holidays.

Add to your agent

Copy this into your MCP client config:

{
  "mcpServers": {
    "tilwhen date engine": {
      "url": "https://mcp.tilwhen.com/mcp",
      "transport": "streamable-http"
    }
  }
}

Measured tools (9)

• parse_date_query read-only

  Parses queries like "90 business days from today in uganda" into a normalized operation, answers it, and returns the auditable receipt. Ambiguous dates (03/04/2027) return needsClarification instead of a guess.

  Parameters:

  • q (required) — string — The date question in plain language. Pass the user's wording rather than a date you computed.
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • locale — string — Resolves ambiguous slash dates; omit to receive clarification choices

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• add_days read-only

  The date N whole calendar days after a date (exclusive counting: the start date is day 0). Omit date for today in tz. For working days use business_days; for the gap between two dates use days_between.

  Parameters:

  • days (required) — integer — Whole calendar days to add. Negative counts backwards.
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • date — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• subtract_days read-only

  The date N whole calendar days before a date (exclusive counting: the start date is day 0). Omit date for today in tz. For working days use business_days; for the gap between two dates use days_between.

  Parameters:

  • days (required) — integer — Whole calendar days to subtract. Negative counts forwards.
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • date — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• days_between read-only

  Signed whole calendar days from the from date to the to date, midnight to midnight in tz: positive when to is later, negative when it is earlier. Endpoints are exclusive, so this is the gap and consecutive dates are 1 apart. Either date may be "today", resolved in tz. For working days between two dates use business_days; to move a date by N days use add_days or subtract_days.

  Parameters:

  • from (required) — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • to (required) — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• business_days read-only

  Span mode (from+to): business days between two dates, exclusive of the start day, inclusive of the end day. Add mode (days, optional date): the date N business days away. Passing from or to selects span mode and needs both; days and date are then ignored, so add mode takes its start date in date, not from. Optional holiday jurisdiction or custom calendar, and a selectable working week. For calendar days use add_days, subtract_days or days_between.

  Parameters:

  • to — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • date — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • days — integer — Add mode: business days to move. Negative counts backwards.
  • from — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • workweek — string — Working week. Default mon-fri (Sat+Sun weekend).
  • jurisdiction — string — Holiday jurisdiction id: US, GB, GB-SCT, GB-NIR, IE, FR, CA, AU, UG (alias UK for GB). No default: omit for no holiday calendar.
  • customHolidays — array — Custom organizational holiday calendar as ISO dates (mutually exclusive with jurisdiction)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• invoice_due read-only

  Due date for Net-N payment terms (calendar days, invoice date = day 0). Optional roll-forward past weekends and, with a jurisdiction or custom calendar, public holidays.

  Parameters:

  • net (required) — integer — Net-N payment terms in calendar days (Net 30 = 30).
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • roll — boolean — Roll a weekend or holiday due date forward to the next business day. Default false.
  • workweek — string — Working week. Default mon-fri (Sat+Sun weekend).
  • invoiceDate — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • jurisdiction — string — Holiday jurisdiction id: US, GB, GB-SCT, GB-NIR, IE, FR, CA, AU, UG (alias UK for GB). No default: omit for no holiday calendar.
  • customHolidays — array — Custom organizational holiday calendar as ISO dates (mutually exclusive with jurisdiction)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• next_occurrence read-only

  The next occurrence strictly after the base date (default today) of either a tracked event slug (e.g. "christmas") or a weekday (0 = Sunday .. 6 = Saturday). Provide exactly one of event/weekday.

  Parameters:

  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • from — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • event — string — Event slug (e.g. christmas). Exactly one of event/weekday.
  • weekday — integer — 0 = Sunday .. 6 = Saturday. Exactly one of event/weekday.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• holidays read-only

  Observed public holidays with the nominal (legal) date and status: rule (statutory) or declared (officially declared for that year). Declared-only holidays are omitted for undeclared years, with a holiday_data_incomplete warning.

  Parameters:

  • jurisdiction (required) — string — Holiday jurisdiction id: US, GB, GB-SCT, GB-NIR, IE, FR, CA, AU, UG (alias UK for GB).
  • year (required) — integer — Calendar year to list, e.g. 2027

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• explain read-only

  Runs any operation and returns the receipt plus human-readable derivation steps. Set op, then pass the fields that operation's own tool takes. Use it when the user asks how an answer was reached.

  Parameters:

  • op (required) — string — Operation to explain. holiday_lookup is the holidays tool; the others share their tool's name.
  • to — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • tz — string — IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.
  • net — integer — Net-N payment terms in calendar days (Net 30 = 30).
  • date — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • days — integer — Day count for add_days, subtract_days and business_days add mode.
  • from — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • roll — boolean — Roll a weekend or holiday due date forward to the next business day. Default false.
  • year — integer — Calendar year for holiday_lookup, e.g. 2027
  • event — string — Event slug (e.g. christmas). Exactly one of event/weekday.
  • weekday — integer — 0 = Sunday .. 6 = Saturday. Exactly one of event/weekday.
  • workweek — string — Working week. Default mon-fri (Sat+Sun weekend).
  • invoiceDate — string — ISO date YYYY-MM-DD, or "today" (resolved in tz)
  • jurisdiction — string — Holiday jurisdiction id: US, GB, GB-SCT, GB-NIR, IE, FR, CA, AU, UG (alias UK for GB). No default: omit for no holiday calendar.
  • customHolidays — array — Custom organizational holiday calendar as ISO dates (mutually exclusive with jurisdiction)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

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