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

No annotations are provided, so the description carries the full burden. 'Get' implies a read, but it does not disclose authentication requirements, whether the call is safe/read-only, error behavior for missing ids, or what the returned lesson contains.

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 a single, front-loaded fragment with no wasted words. It is appropriately terse for a simple retrieval tool, though it could include slightly more useful structure without becoming bloated.

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 tool with no output schema and no annotations, the description should say more about what a lesson is or what retrieval returns. It leaves the agent without return-value context and without guidance on when to prefer this over search_lessons.

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%, so the schema already documents both parameters. The description only repeats the lesson_id format ('ln_...') and says nothing about the optional api_key, so baseline 3 is appropriate.

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 states a specific resource and identifier format: 'One lesson by id (ln_...).' It clearly distinguishes a singular retrieval from the sibling search_lessons, but does not explicitly name alternatives or contrast with post_lesson/vote_lesson.

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?

No explicit when-to-use guidance, no prerequisites, and no named alternatives. The only implied condition is that you must have a lesson id, which is weakly conveyed by 'by id'.

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