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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real value: the exact holiday layers counted vs. not inferred (regional, municipal, bank, exchange, employer agreements), the substitute-day policy, the 28 October note, a change-detection formula, and an explicit REST fallback path. It stops short of stating rate limits or range-size constraints.

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?

Sectioned and mostly front-loaded, but padded: the Outputs enumeration duplicates fields already in the output schema, the Formula line restates the obvious, and the malformed 'Do not use this when...' sentence costs clarity without earning its 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?

With annotations carrying the safety profile and an output schema covering return fields, the description need not explain results; it does cover scope limits, examples, and a fallback endpoint. The one gap is the effective calendar window (the schema hints 2026-2026) not being restated in prose.

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 all four parameters (including the optional include_start_date/include_end_date) are already documented, and the description largely repeats them ('Inputs: start_date (date); end_date (date)...'). The complete JSON argument example is a marginal addition over the schema's own examples, so the baseline 3 applies.

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?

States a specific verb+resource for a specific authority scope ('Counts authority-scope working and non-working dates in a range') and the country is explicit in the name/title. It is clearly distinguishable from the sibling check_gr_working_day (single-date test) and add_gr_working_days (arithmetic shift), and it even includes worked example requests.

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?

Opens with when to use it ('auditable Greece working-day count') and explicitly instructs to call the tool directly rather than answer from memory. It also attempts a when-not-to-use clause, but that sentence is garbled ('Do not use this when this package covers the nationwide compulsory public-holiday layer...') and never names the sibling tools it competes with.

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