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

Annotations already declare this a safe, idempotent read, so the description earns credit for the non-obvious behavioral detail: output varies by lesson tier, with full text/video for previews and only a summary plus sign-in link otherwise. The auth prerequisite is disclosed. It stops short of describing not-found or invalid-course 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?

Two sentences, zero filler, and the most decision-relevant fact (preview vs gated content) is placed immediately after the core action.

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 present, the description must explain return values, and it does so for both content tiers plus the auth requirement. It leaves only edge cases (missing lesson, invalid course) unspecified.

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% for both parameters, including the hint that lesson ids come from get_course_outline. The description adds nothing about accepted id/title formats, so the baseline of 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+resource ("Get a lesson"), and the follow-on sentences make clear it retrieves lesson content rather than course structure or mentor listings. It does not explicitly name or contrast a sibling, but the name is unambiguous against get_course_outline/list_courses.

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 description implies usage context (available as a preview, otherwise gated behind a free mentor.energy account) but never states when to call this versus get_course_outline or search. The lesson id source is only mentioned in the schema, not in the description.

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