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

The description adds important behavioral context beyond the annotations: the `source` field can be `fallback`, meaning times are a saved snapshot, and the agent must explicitly say so. This discloses a non-obvious reliability characteristic that the readOnly/idempotent annotations do not convey.

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 two concise sentences, with the core resource and scope front-loaded, followed by the essential fallback caveat. There is no filler or repetition of structured data.

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?

For a parameterless, read-only lookup tool with annotations covering safety, the description is complete: it states the cities, the time period, the returned content (candles, havdalah, parasha), and the critical fallback behavior. No output schema exists, so the description adequately carries the information an agent needs.

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 tool has zero parameters and the schema is an empty object, so the description cannot add parameter-level meaning. The baseline of 4 applies because there are no parameters to document, and the description instead clarifies the output semantics tied to the `source` field.

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 the exact resource (candle lighting and havdalah times), the time scope (current week), and the geographic scope (six specific Moroccan cities), plus the parasha. This clearly distinguishes it from siblings like get_hilulot or get_city_guides, which cover different content.

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?

Usage context is implied: it is the tool for current-week Shabbat times in the listed Moroccan cities. However, it gives no explicit when-to-use or when-not-to-use guidance, and does not mention alternatives or exclusions, so an agent must infer when this is the right choice.

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