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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered; the description adds genuinely new context about payload contents (every lesson has a lesson plan, exit ticket and practice; a unit adds pre-check, review and test). It says nothing about result volume, pagination, or what happens with an out-of-range grade/unit.

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?

Three short, front-loaded sentences that map one-to-one onto the three call shapes, with zero filler. The telegraphic 'Without a grade: the list' phrasing is efficient but slightly clipped, costing a little readability.

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 carries the burden of describing returns and does so at the right level (what each mode yields, what each lesson/unit contains). Remaining gap is only edge behavior — dependency between unit and grade, and invalid-value handling — which is minor for a read-only lookup.

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 100%, so the baseline is 3; the description earns above that by explaining the semantics of the combination — grade alone returns units and lessons by number, adding unit drills into that unit's lessons and assessments. The only gap is whether unit can be supplied without grade, which neither schema nor description resolves.

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?

Names the concrete resource (Animal Math's free full-year math curricula, K-5) and the exact payload for each input combination: grade list, grade's units and lessons, or a single unit's lessons plus pre-check/review/test. It never names its siblings, though, so the boundary with get_lesson (single-lesson detail) and search_resources is left for the agent to infer.

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?

Effectively documents three usage modes keyed to parameters ('Without a grade', 'With a grade', 'With a unit too'), which is clear conditional guidance for a no-required-param tool. It stops short of stating when to prefer get_lesson or search_resources instead, so no explicit alternatives or exclusions.

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