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

With readOnlyHint=true already indicating a safe read, the description adds meaningful behavior: the mode switch when chabbat=true (Shabbat schedule instead of daily zmanim) and the data source (Hebcal). It does not cover edge cases like parameter conflicts or error handling, but it adds value beyond the annotation without contradiction.

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 description is a single, front-loaded sentence with a parenthetical list of zmanim, followed by two short clarifying sentences. Every word contributes; there is no filler or repetition of schema details. Highly concise and well structured.

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?

Even without an output schema, the description lists the return categories (alot, netz, ..., chabbat times, paracha), explains location options, and names the data source. It does not cover response format or error conditions, but for this type of calendar tool the description is arguably complete enough for an agent to invoke it correctly.

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?

The schema already documents most parameters, but the description adds semantic context by grouping 'Villes prédéfinies ou coordonnées libres', which clarifies how ville, geonameid, latitude/longitude/tzid relate. It also reinforces the chabbat boolean meaning. This compensates for the undocumented latitude/longitude fields, going beyond the schema's baseline.

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 clearly identifies the resource (daily Jewish prayer times) and the specific verb/function ('Zmanim du jour', returns times like alot, netz, shkia, etc.). It also distinguishes the Shabbat mode via 'chabbat=true'. However, it does not explicitly contrast with sibling tools such as sefaria_calendar, so it stops short of full sibling differentiation.

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 description provides clear usage context: daily zmanim by default, Shabbat entry/exit and paracha when chabbat=true, and input via predefined cities or free coordinates. It does not explicitly mention alternatives or when not to use this tool, but the guidance is sufficient for typical selection.

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