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

With readOnlyHint already covering safety, the description adds useful context: Hebcal is the data source, chabbat=true switches the output mode, and locations can be predefined or coordinates. However, it does not describe output shape, timezone defaults, or behavior on invalid input, so it remains moderate.

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?

Three short sentences front-load the main output, then the mode switch, data source, and location options. There is no filler, no repetition of schema detail, and every sentence contributes to selecting a valid call.

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?

Together with the rich schema, the description gives an agent enough context to call the tool: what date to pass, how to choose a location, and what output to expect. Minor gaps such as output serialization and invalid-location behavior remain, but they are not blocking for a read-only calendar tool.

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 describes 5 of 7 parameters in detail, and the description's 'chabbat=true' and 'coordonnées libres' phrases mostly restate those existing constraints. It adds only a light conceptual link between the mode flag and the returned content, without enriching per-parameter meaning much.

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 ('Zmanim du jour') and lists the returned items (alot, netz, sof zman, etc.), then specifies the chabbat=true behavior for Shabbat entry/exit times and paracha. It does not explicitly contrast with sibling tools such as sefaria_calendar or guide_paracha, so it misses the top score.

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 gives explicit conditional guidance: use chabbat=true for Shabbat times, and choose either predefined villes or free coordinates. It does not name alternative tools or say when not to use this tool, so it stops short of full routing guidance.

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