Calcgrid

Add UK Working Days

add_uk_working_days

Read-onlyIdempotent

Use this when you need a deadline a stated number of UK working days before or after a 2024-2028 date and the correct division's bank holidays matter. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery.

Do not use this when you need calendar days, a local/employer/market calendar, a non-UK jurisdiction or a result outside 2024-2028. What it computes: Adds or subtracts working days for England and Wales, Scotland or Northern Ireland, skipping weekends and the selected division's official bank holidays. Example user requests: What date is five England and Wales working days after 23 December 2026? | Add two Scottish working days to 12 June 2026, accounting for the official bank holiday. | Subtract ten Northern Ireland business days from 20 July 2027. Inputs: start_date (date); working_days (integer, working days); division (enum, optional). Complete JSON argument examples: {"start_date":"2026-12-23","working_days":5,"division":"england-and-wales"} | {"start_date":"2026-06-12","working_days":2,"division":"scotland"} Outputs: division, division_name, start_date, result_date, result_weekday, result_is_working_day, working_days_added [working days], calendar_days_elapsed [days], non_working_days_skipped [days], bank_holidays_skipped, dataset_version, coverage_start, coverage_end, source_snapshot_sha256. Formula: move one calendar day at a time in sign(working_days); decrement only when the selected UK division reports is_working_day=true Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/uk-add-working-days with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/everyday/uk-add-working-days.md

Input Schema

TableJSON Schema

Name	Required	Description	Default
`division`	No	GOV.UK bank-holiday division. England and Wales share one official list; Scotland and Northern Ireland have separate lists.	england-and-wales
`start_date`	Yes	Starting UK civil date in YYYY-MM-DD format, within 2024-2028.
`working_days`	Yes	Signed working-day offset. The start date is excluded when non-zero; negative values move backward. Unit: working days.

Output Schema

TableJSON Schema

Name	Required	Description
`links`	No
`result`	Yes
`request`	Yes
`sources`	No
`success`	Yes
`version`	No
`freshness`	No
`timestamp`	Yes
`next_actions`	No
`service_version`	Yes	Deployed Calcgrid implementation version used for the result.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 27, 2026

addedOutput schema / properties / service_version

Added value: +{
+  "description": "Deployed Calcgrid implementation version used for the result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "success",
-  "request",
-  "result",
-  "timestamp"
-]New value: +[
+  "success",
+  "service_version",
+  "request",
+  "result",
+  "timestamp"
+]

AddedSep 26, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already declare readOnly, idempotent, and non-destructive behavior, so the description adds substantial beyond-annotation context: the exact iteration formula, the division-specific holiday handling, the date-range boundary, and the direct REST fallback. This gives the agent an accurate model of how the computation behaves.

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?

The description is longer than minimal, but its content is organized into clear sections: when to use, when not to use, computation details, examples, outputs, formula, and fallback. It is front-loaded with the critical selection criteria, and nearly every sentence adds practical value.

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

Completeness5/5

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

Given the 3-parameter schema, rich annotations, output schema, and sibling context, this description is complete. It covers selection criteria, exclusions, examples, calculation semantics, output fields, coverage bounds, and even a REST fallback endpoint. An agent has everything needed to invoke it correctly.

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

Parameters4/5

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

The input schema already covers 100% of parameters with types, defaults, enums, and descriptions, so the baseline is 3. The description adds meaning beyond the schema by explaining the signed working-day formula, providing complete JSON examples, and clarifying how the division choice affects the calculation.

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

Purpose5/5

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

The description identifies an unambiguous verb and resource: it adds or subtracts UK working days for England and Wales, Scotland, or Northern Ireland. It also distinguishes itself from related tools by emphasizing the division-specific bank holidays and the 2024-2028 coverage window.

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

Usage Guidelines5/5

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

The description opens with explicit 'Use this when' conditions and provides direct 'Do not use when' exclusions for calendar days, local/employer/market calendars, non-UK jurisdictions, and dates outside 2024-2028. It also tells the agent to call the tool directly rather than compute the answer from memory, which is strong selection guidance.

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

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