Vacances, jours fériés et soleil à La Réunion

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

Annotations already declare readOnlyHint, openWorldHint and idempotentHint, so the safety profile is covered. The description adds domain-relevant behavior: the calendar is austral and diverges from the metropole, and an empty place yields an island-wide result. It says nothing about caching, data freshness, or how ambiguous place names are resolved — relevant given openWorldHint with free-text geocoding.

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 data inventory is front-loaded in the first sentence and the sample queries follow as retrieval aids. There is some redundancy — the trailing English sentence re-summarizes a subset of what the French already said — but the overall length is proportionate to four distinct data domains.

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 one optional parameter, full schema coverage, and annotations, the main remaining burden is telling the agent what data comes back — which the description does by enumerating holidays, vacations, date, and sun times. It never indicates the response shape (e.g. list of upcoming holidays vs. a single date), a minor gap since no output schema exists.

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% and the `lieu` parameter is already richly documented in the schema (commune, beach, cirque, summit, or 'lat, lon'; empty = whole island). The description only restates 'au lieu demandé', so it adds nothing beyond structured data — 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?

The description names concrete resources — school holidays for the Réunion academy (austral calendar, explicitly different from metropolitan France), public holidays including 20 December Fèt Kaf, today's date, and sunrise/sunset for a given place. It is clearly separable from every sibling tool, which are all weather/air/seismic/public-service tools.

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?

The 'Pour : « c'est quand les vacances ? »…' list gives explicit natural-language triggers, including an edge case for sunrise at a specific summit (Maïdo), which directly maps to the `lieu` parameter. It stops short of naming when NOT to use it — e.g. that day-to-day weather belongs to meteo_actuelle/prevision_meteo rather than this tool.

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