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

Annotations declare readOnlyHint=true, so the safety profile is already covered. In exchange, the description adds real behavioral context by disclosing what the response contains (students, statuses, charges, notes, teacher, wage, cost) — valuable since there is no output schema. It stops short of noting failure modes for a non-existent id, which keeps it from a 5.

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?

One sentence that front-loads the verb and payload summary, followed by the HTTP route. Zero filler; every clause carries information.

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-record GET with one required id and no output schema, the description supplies a useful return-field inventory so the agent knows what it will get. Missing only edge-case behavior (unknown id, permissions), which is minor at this complexity.

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?

Only one parameter, and the schema already documents it at 100% coverage ('Lesson id.'). The description adds no format, range, or lookup guidance beyond what the schema provides, so 3 is the correct baseline.

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 ('Retrieve one lesson') and enumerates the payload (participants, teacher, wage, cost). The singular object makes it distinguishable from teachworks_list_lessons and the breakdown distinguishes it from teachworks_get_lesson_totals, though neither sibling is named explicitly.

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?

Usage is implied by the required lesson_id and the single-record framing: use this when you already know which lesson you want. There is no explicit when-to-use statement, no mention of when to prefer list_lessons or get_lesson_totals instead, and no prerequisites.

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