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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds a genuinely useful trait beyond the schema: 'Moderate cost', which helps the agent budget calls. It also reinforces the anonymous-handle requirement, though it omits pagination/return-shape notes (partly covered by the output schema).

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 tight sentences, front-loaded with the returned content so an agent sees the payload scope first, then the input, then the cost. No filler, though the handle restatement is slightly redundant with the schema.

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 an output schema present, the return values need not be described, and the description still names the key outputs, the input format, and the cost. It is complete enough to call correctly; only explicit sibling routing is missing.

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 schema already documents all five parameters, including the S-… handle pattern and the days semantics. The description's 'Accepts an anonymous student handle (S-…)' merely restates schema content, so baseline 3 applies.

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?

States a specific verb and resource ('Returns one student's Fiveable work') and enumerates the concrete outputs (average, missing work, assignment scores, weakest units, skill progress). The scoping word 'one student's' implicitly distinguishes it from the sibling get_class_insights, though it never names the sibling 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?

Provides use contexts ('conference preparation, parent notes and individual reteaching'), which implies when the tool is appropriate. However it gives no explicit alternatives (e.g. get_class_insights for aggregate views) and no exclusions, leaving the agent to infer routing.

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