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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds one useful semantic point — lesson quizzes are study checks, not IELTS scores — but says nothing about return shape, pagination, or ordering.

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 tight sentences, front-loaded with the primary action. The trailing quiz clarification earns its place but is slightly tangential to the tool's mechanical behavior.

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 simple two-parameter read tool with annotations covering safety, this is close to sufficient. The absence of any listing output description (fields per lesson, ordering, whether lessonId is required vs. optional) leaves a small but real gap given there is no output schema.

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 0%, so the description must carry parameter meaning. It does partially: 'writing or speaking' maps to the area enum and 'read one lesson in full by ID' maps to lessonId, but neither parameter is named or given format/validation detail.

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 and resource ('List the ... lessons') and adds a second mode ('read one lesson in full by ID'). The scope is clear and distinguishable from siblings like analyze_writing and get_sample_answer, though it never explicitly names an alternative.

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 two modes (list all vs. fetch one by ID) imply when each is used, and the note about quizzes clarifies a study-check vs. IELTS-score distinction. However, no sibling is named and there is no explicit when-not guidance for a tool sitting next to search_practice and get_sample_answer.

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