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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context beyond the annotations: a 'Moderate cost' signal and the ordering convention ('weakest first'), which help an agent decide whether and how to call it.

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 dense sentences with the returned content front-loaded, followed by the scoping and cost note. No redundant restatement of the name or obvious 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?

An output schema exists, so return values need not be described; the description still covers content, scope, ordering, and cost. It is essentially complete, missing only explicit routing to sibling insight tools.

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?

With 100% schema coverage the baseline is 3, and the description goes further by naming the four scoping dimensions (class, subject, assignment, time window) that map onto classId, subjectSlug, assignmentId, and days, reinforcing how each parameter narrows the query.

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 (class insights) and enumerates exactly what is returned: accuracy and FRQ points over time, per-assignment turn-in rate and average, and per-student averages with flags. It is clearly class-scoped, implicitly distinguishing it from get_student_insights and get_skill_insights, though it never names those siblings explicitly.

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 states the scoping dimensions ('Scope by class, subject, assignment or time window') and gives a cost signal ('Moderate cost'), which impliedly guides use. But it never states when to prefer this over get_student_insights, get_skill_insights, or get_reteach_gaps, leaving alternative selection to inference.

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