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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the result set widens to every class when grade/class are omitted, which is not inferable from the annotations and matters for result interpretation.

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, no filler, with the resource and scope front-loaded and the filtering caveat immediately after. Every clause carries information an agent can act on.

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 five-parameter read-only lookup with no output schema, the definition covers purpose, scope and filter-omission behavior adequately. It does not describe the shape or volume of the returned period/subject data, but that gap is minor given the annotations and the low complexity.

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 100%, so the baseline is 3; grade, class_name, eduCode and schoolCode are already documented with formats and examples in the schema. The description only adds omission semantics for grade/class, which is a useful but marginal increment over the schema.

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 gives a specific verb and resource ('Class timetable (period and subject)') plus the scoping dimensions (school, grade, class, day), so an agent knows exactly what it returns. It does not explicitly distinguish itself from the sibling get_schedule, which leaves a small ambiguity about which to pick for schedule-like data.

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?

'Without grade/class it returns every class, so pass them when known' tells the agent when to include the optional filters and what happens if it doesn't. It stops short of naming an alternative tool or stating exclusions, so it is clear context rather than full when/when-not routing.

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