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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description still adds real value by disclosing the shape and ranking logic of the result: band values, why the next three topics were chosen (weak first, then too-few-marks, then ready untried topics, each with a reason), and that practise links are included.

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?

It is one front-loaded sentence that leads with the resource and scope before enumerating outputs; every clause carries information. The nested parenthetical is dense but not wasteful.

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 takes on the job of describing return content, which it does thoroughly for a one-parameter read tool. Minor gaps remain: no mention of behavior when the student is unlinked or the subject code has no data, and no note on permissions.

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?

There is a single parameter with 100% schema description coverage including a pattern and examples, so the schema carries the semantic load. The description only restates the notion of 'one subject' without adding format or constraint detail beyond the schema; 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?

The description names a specific resource and scope: the linked student's own progress in one subject, broken into per-topic bands, a prioritized next-three list, and practise links. That is clearly distinct from siblings such as class_summary (aggregate) and common_mistakes (error-focused).

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?

Usage is only implied: 'the linked student's own progress' tells the agent this is student-scoped rather than class-scoped, but there is no explicit when-to-use or when-not, and no sibling is named as an alternative for adjacent questions like common_mistakes or find_questions_by_topic.

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