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

Annotations already declare readOnlyHint=true. The description adds meaningful behavioral context beyond that: it explicitly says the verse is actually read via Sefaria, times come from Hebcal, and the user can then request personalization. There is no contradiction with the read-only annotation.

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?

Two sentences, front-loaded with the verb and deliverable, then a compact list of contents. The first sentence is long but every element contributes to the expected output; the second sentence adds a clear conditional. No filler.

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 still enumerates the five content pieces (parsha name, Hebrew, reference, French verse, times, link) and the optionality around city. It also anticipates the likely follow-up request. Exact formatting is not specified, but enough is given for correct invocation.

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 coverage is 60%, with latitude and longitude undocumented in the schema. The description adds the key semantic distinction that providing a city enables times and omitting it omits times, but it does not explain the coordinate/tzid grouping or compensate fully for the undocumented parameters.

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 verb and resource: 'Compose le petit mot de Chabbat de la semaine, prêt à envoyer sur WhatsApp', then enumerates the message components. It clearly differentiates this tool's combined output from narrower tools, though it never explicitly names or excludes siblings, 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?

It provides clear usage context: users who want a shareable weekly Shabbat message with parsha, verse, times, and study link. The conditional 'Sans ville, le mot est composé sans les horaires' clarifies behavior based on input, but no alternatives or when-not-to-use guidance is given.

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