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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds genuine behavioral context beyond those annotations by revealing exactly what the fetch returns and confirming it retrieves the entire topic rather than a fragment. It does not mention error cases or format details, but with the annotations the bar is lower.

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 sentences, each earning its place: the first states the action and output contents, the second gives usage circumstances, and the third gives the required prerequisite. The purpose is front-loaded and no filler is present.

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 single-parameter read-only tool with no output schema, the description is complete: it explains what the tool returns, when to call it, and how to obtain the required lessonKey. An agent has everything needed to select and invoke it correctly.

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 the schema already explains that lessonKey is a lesson key sourced from list_curriculum. The description reinforces the need to obtain the key first but does not add new semantic detail about the parameter itself, 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?

The description states a specific verb ('Fetch'), a precise resource ('one full ground-school lesson'), and enumerates what is returned: summary, why it matters, learning objectives, and a link. It also routes the agent away from search_faa_knowledge and toward list_curriculum, clearly distinguishing itself from the sibling tools.

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 explicitly says when to use this tool ('after search_faa_knowledge when the user wants the whole topic rather than a single answer' or 'when they ask to study or learn a subject properly') and names the prerequisite alternative ('Call list_curriculum first if you do not already have a lesson key'). This is actionable, unambiguous routing guidance.

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