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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description's extra value is naming the returned sub-fields, but an output schema exists, so this usefully hints at content shape without telling the agent anything the structured data does not already carry.

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?

A single compact sentence that front-loads the resource and then lists the payload contents. It is not padded, though as a noun phrase fragment it omits a verb and reads more like a title expansion than a full description.

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 full schema coverage, complete annotations and an output schema, the description is just barely sufficient. The missing piece is routing guidance — when to reach for get_course versus list_courses or get_plan — which no structured field supplies.

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%: course_id is documented as coming from list_courses and lang is documented with its zh/en enum. The description adds nothing about either parameter, which is the expected baseline when the schema does the heavy lifting.

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 the resource (one course) and enumerates its content — lessons with objective, key points, practice task and knowledge check — so an agent knows this returns a single course's instructional payload. It does not explicitly contrast with get_plan or get_source_page, but the resource noun is specific enough to distinguish it from the list_courses sibling.

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 when-to-use statement, no prerequisites, and no mention of alternatives such as list_courses (which the course_id schema description implies as a prior step). Usage must be inferred entirely from the name and schema.

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