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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely useful behavioral context beyond them: the content deliberately omits answers and quiz keys, which prevents an agent from misreading the payload as incomplete or retrying for missing data. It says nothing about size, pagination, or the language-switching behavior, so it is not exhaustive.

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 sentences, zero filler, with the content inventory up front and the answer-withholding caveat plus redirect to check_answer at the end. The middle clause is a dense comma-list that is slightly harder to scan than a structured breakdown, but every element earns its place.

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?

There is no output schema, so the description correctly spends its words telling the agent what a lesson payload contains, which is exactly the missing piece. Combined with the intentional-omission note, an agent can call this correctly and interpret the result. Minor gaps remain around ordering, size, and the relationship to explain_concept.

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% and both parameters carry enums with their own descriptions, including the note that the course stays in English for non-en languages. The description adds no parameter-level meaning of its own. A 3 baseline is appropriate where the schema does the work.

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 clearly scopes the tool to a single lesson of a course and enumerates its contents (question, three-depth explanation, formula, line-by-line script, exercises with hints, quiz, flashcards), which effectively distinguishes it from get_code and explain_concept. It never states a verb like 'return' or 'retrieve', so the action is inferred from 'One lesson of the course', keeping it short of a 5.

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 gives an explicit routing rule for the main ambiguity: exercise answers and quiz keys are withheld, so the agent should call check_answer after the learner has tried. That is concrete when-to-use guidance tied to a named sibling. It does not address when to prefer explain_concept or get_code over a full lesson, so the coverage of alternatives is partial rather than complete.

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