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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine value by explaining the day_off=true distinction for yom tov, which is the one output behavior an agent must anticipate. It does not say what happens when year is omitted or whether the result is a list of objects vs. dates.

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?

One short sentence with the key qualifier (day_off/yom tov) front-loaded and no filler. It is arguably too terse given the undeclared parameter, but nothing is wasted.

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 single-parameter read-only tool with rich annotations and no output schema, the description covers the headline output semantic but omits the year default/range and any sense of return shape. Adequate to call correctly, not quite complete.

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 description coverage is 0% and there is a single optional 'year' parameter with bounds 2000-2100 and no default documented anywhere. The description only says 'for a year' without stating the range, the default behavior when omitted (required parameters = 0), or the expected format, so it fails to compensate for the coverage gap.

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 a specific resource (Jewish/Israeli holidays) and scopes it to a year, which distinguishes it from the nearest sibling, shabbat_times. It is a noun phrase rather than a verb+resource, but the intent is unambiguous.

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?

There is no indication of when to use this versus shabbat_times or other calendar-adjacent siblings, nor any prerequisites or exclusions. The day_off note clarifies output semantics rather than usage, leaving the agent to infer applicability.

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