Hopi

Working days calculator

hopi_working_days_calculator

Read-onlyIdempotent

Count the working days (Monday to Friday) between two dates, inclusive of both ends, optionally excluding England and Wales bank holidays. Dates use the YYYY-MM-DD format. Bank holiday data covers 2026 and 2027 only, so outside those years just weekends are excluded. Source: https://hopi.co.uk/working-days-calculator/

Input Schema

TableJSON Schema

Name	Required	Description
`to`	Yes	End date in YYYY-MM-DD format
`from`	Yes	Start date in YYYY-MM-DD format
`bankHolidays`	No	Exclude England and Wales bank holidays as well as weekends (default true)

Output Schema

TableJSON Schema

Name	Required	Description
`to`	No
`from`	No
`summary`	Yes
`swapped`	No
`complete`	No
`warnings`	No
`totalDays`	No
`source_url`	Yes	The tool's page on hopi.co.uk (cite or open to check the figure)
`weekendDays`	No
`workingDays`	No
`bankHolidays`	No
`holidayCoverage`	No
`bankHolidaysExcluded`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedSep 20, 2026
- addedOutput schema / properties / complete
```
Added value: +{
+  "type": "boolean"
+}
```
- addedOutput schema / properties / holidayCoverage
```
Added value: +{
+  "type": "object"
+}
```
- addedOutput schema / properties / warnings
```
Added value: +{
+  "type": "array"
+}
```
- addedOutput schema / required
```
Added value: +[
+  "source_url",
+  "summary"
+]
```
First observedSep 20, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, establishing a safe, non-mutating operation. The description adds valuable behavioral context beyond annotations: dates are inclusive of both ends, only England and Wales bank holidays are considered, and the bank holiday dataset is limited to 2026–2027, outside which only weekends are excluded. This information meaningfully affects results and is not available from annotations alone.

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 compact and front-loaded, with the core action in the first sentence and important caveats following. Every sentence contributes useful information, though the source URL is auxiliary rather than essential for invocation. Overall it is appropriately sized and easy to parse.

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?

The description covers the core inputs, date format, inclusivity, bank holiday behavior, and the critical 2026–2027 data limitation. With an output schema present, return value details are not required. It does not specify behavior for reversed dates or invalid input, but that is a minor gap given the schema and simple nature of the operation.

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?

Schema coverage is 100%, so parameters are already documented with names and descriptions. The description adds semantic value by clarifying 'inclusive of both ends' and the bank holiday data limitation, which affect how the 'from', 'to', and 'bankHolidays' parameters should be interpreted. It also reinforces the YYYY-MM-DD format required by the schema.

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 uses a specific verb, 'Count', and a precise resource, 'working days (Monday to Friday) between two dates', making the tool's purpose immediately clear. It also states key scope details—inclusive of both ends and optional bank holiday exclusion—which distinguishes it from related siblings like hopi_days_between_dates. The name, title, and description align.

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

Usage Guidelines4/5

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

The description clearly sets the context: use this calculator when you need working days between two dates, with optional bank holiday exclusion. It does not explicitly name alternatives or exclusion conditions, but the 'working days' focus and bank holiday option sufficiently guide an agent. The 2026–2027 data coverage caveat prevents incorrect use for other years.

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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