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

Annotations already declare readOnly/idempotent/non-destructive/non-open-world, so the bar is lower. Beyond that, the description adds real behavioral context: the deterministic nature, the explicit formula, the warning that Islamic dates and later PM decisions require a refreshed package, and a direct REST fallback URL with a warning not to guess other paths.

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

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

It is front-loaded with the primary use case, but there is noticeable redundancy and noise: the duplicated 'Egypt Egypt', the awkward 'Do not use this when this package covers' clause, and the '2026-2026' range. Several sentences only partially earn their place.

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

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

All the pieces an agent needs are present: scope, formula, inputs/outputs, a REST fallback, and docs link, and an output schema exists so return values need not be explained. Minor incompleteness comes from the confusing exclusion sentence rather than missing information.

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

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

There is only one parameter and schema description coverage is 100%, so the schema already carries the semantics; the description adds the example argument forms and restates the date's meaning. No additional syntax beyond the schema is introduced, hence not a 5.

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

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

The description names a specific verb and resource ('checks a date against the Friday-Saturday weekend baseline and exact 2026 authority events') and the tool name itself differentiates it from the many check_XX_working_day siblings by country. It is slightly muddied by the garbled opening ('Egypt Egypt 2026 official public-holiday layer') and a run-on list of covered bodies, but an agent can still identify the operation.

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

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

It gives explicit when-to-use ('when you need a deterministic Egypt ... layer') and enumerates when-not-to-use/won't-cover cases (private employers, banks, schools, diplomatic missions, exchanges, local/sector calendars). The 'Do not use this when this package covers...' sentence is syntactically broken and confusing, but the exclusion list still conveys the boundaries.

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