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

Annotations already establish read-only, idempotent, non-destructive behavior, so the description is free to spend its words on what the computation returns (needed score per target, reachability, points needed, what-if grades). It also discloses the key modeling limitation that the final is treated as a separate weight and not a weighted-category component, which is exactly the kind of caveat annotations cannot convey.

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?

Front-loaded with the triggering situation before the mechanics, and the closing assumption sentence is well placed. The first sentence is long with several quoted examples, but each clause carries routing value rather than 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?

With an output schema present, the description need not restate return values, yet it still summarizes them and flags the reachability and points-needed outputs. Combined with annotations and full schema coverage, nothing an agent needs to select or call this tool 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 parameters are already fully documented, and the description mostly paraphrases them (current grade, final weight, targets, default all letters). The one genuinely additive note is the 'students or current_grade' framing for the teacher case, which the schema also states, so the 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 ('calculate the score needed on the final') and enumerates the exact user phrasings that should route here. It is clearly distinct from calculate_class_grades and generate_progress_reports because it is per-final, per-target, not an aggregate report.

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?

Gives concrete triggering utterances ('what do I need on my final to get a B', 'score needed to pass') plus a teacher scenario, which is strong when-to-use guidance. It does not explicitly say when to prefer a sibling tool instead, so it stops short of a 5.

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