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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds that the response includes status, scenario, timing, and progress, which is modest but real value beyond the annotations; it does not describe format, pagination, or error behavior.

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?

A single compact fragment, front-loaded and free of filler. It is arguably under-specified rather than overly verbose, but as conciseness it is efficient.

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?

For a read-only tool with no output schema, the description gives at least a preview of the returned fields, and annotations carry the safety context. Still missing are the meaning of lesson_id and any hint of how the result relates to sibling lesson tools, leaving gaps for correct invocation.

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?

The single required parameter lesson_id has 0% schema description coverage, and the description never mentions it or its acceptable values (e.g., whether it is an ID, slug, or the same identifier used by lesson_open). With only one param the burden was small, yet the description does not compensate for the coverage gap.

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 fragment 'The whole lesson for the window' plus the name/title conveys that it fetches a complete lesson, and it lists the returned facets (status, scenario, timing, progress). However, 'the window' is undefined jargon, and it does not distinguish itself from close siblings like lesson_open, lesson_progress, or lesson_create.

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?

There is no statement of when to use this tool versus lesson_open, lesson_progress, or lessons. The agent must infer usage purely from the name and the ambiguous phrase 'for the window'.

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