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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond that by disclosing the response contents (correctness, correct letters, explanation), which tells the agent it is a pure evaluation call with no state change. It stops short of stating whether answers are recorded as progress/mastery.

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 sentences: purpose, the one ambiguous parameter's format, and the return shape. Front-loaded and zero 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 the brief return summary is a bonus rather than a necessity. The only real gap is the format of `exam` (identifier vs. slug) and the exact shape of `question_id` as produced by get_practice_questions — worth one clause given 0% schema coverage.

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 0%, so the description has to carry all three parameters. It fully disambiguates `selected` with concrete examples (["B"], ["A", "D"]), which is the parameter most likely to be mis-formed, but leaves `exam` and `question_id` entirely unexplained — their expected format and provenance must be inferred from get_practice_questions.

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 ('check the user's answer') and immediately anchors it to the sibling that produces the input ('a question from get_practice_questions'). An agent can tell this apart from the read-only exam/practice retrieval siblings without opening a schema.

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?

The workflow dependency is explicit: this is the tool to call on a question returned by get_practice_questions. It does not spell out when NOT to use it or name alternatives, but for a grading endpoint the sequencing guidance is effectively complete.

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