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

Beyond the readOnlyHint annotation, the description adds meaningful behavioral detail: the verse is actually read via Sefaria, the times come from Hebcal, and omitting a city removes the schedule section. This helps the agent understand the tool's conditional behavior and external dependencies.

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 front-loaded with the main action and is information-dense. It is slightly dense as one long sentence with parenthetical additions, but every clause earns its place and no redundant filler is present.

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 no output schema, the description does a good job enumerating the returned message components: paracha details, the French verse, lighting/end times, and a study link. It leaves minor uncertainty about exact formatting or unknown-city handling, but those are partly covered by the schema and the stated no-city rule.

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 description only relates parameters to behavior at a high level ('pour la ville donnée', 'Sans ville, le mot est composé sans les horaires'). It does not explain the latitude/longitude/geonameid alternatives, leaving the schema to carry that meaning; with 60% schema coverage, this is a marginal gap rather than a severe one.

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 opens with a specific action and deliverable: 'Compose le petit mot de Chabbat de la semaine, prêt à envoyer sur WhatsApp', then lists the concrete contents (paracha, verset, horaires, lien d'étude). This clearly differentiates it from sibling navigation or study tools such as zmanim, guide_paracha, or sefaria_search.

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 provides clear context: this is the weekly Shabbat-message generator for sharing on WhatsApp, and it explicitly states the no-city behavior. It does not name alternative tools or exclusions, but the composite purpose makes the usage situation clear enough.

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