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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description goes well beyond them: it discloses the weekend baseline (Friday-Saturday), the government/public-sector authority scope, exclusions for private employers and special operating-hour decisions, the Islamic-date refresh requirement, and the exact formula. The redundancy of listing output fields and the REST fallback dilutes this slightly.

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?

The usage guidance is front-loaded correctly, but the body is bloated with a formula line, a full output-field list that duplicates the output schema, a REST fallback URL, and a docs link. The example user requests include an odd placeholder ('Ordinary Egypt working day') that adds noise rather than clarity.

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?

Given an output schema exists, the return-value enumeration is unnecessary, but the description still supplies the scope, weekend baseline, refresh caveat, and computation semantics an agent needs. It is complete enough to call correctly, though the confusing 'Do not use this when' clause and redundant output list keep it from being fully polished.

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?

Schema description coverage is 100%, so the schema already documents all four parameters and their defaults, which sets the baseline at 3. The description restates the parameter list and provides a full JSON example, adding only marginal value beyond the schema's own examples.

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 states a specific verb and resource -- counting authority-scope working and non-working dates in a range for Egypt -- so an agent can tell it apart from the country-specific siblings. It does not, however, explicitly distinguish itself from the closely related check_eg_working_day or add_eg_working_days, leaving that inference to the agent.

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 clear triggering context ('Use this when you need an auditable Egypt working-day count') and an explicit instruction to compute rather than answer from memory. The 'Do not use this when...' sentence, however, is garbled and reads as a scope caveat rather than a real when-not-to-use rule, so the routing guidance is only partly actionable.

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