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

Annotations already declare readOnlyHint=false and destructiveHint=false; the description usefully adds that the parent class survives, which explains why destructiveHint is false. However, it omits whether the cancellation is reversible (restore_lesson suggests it is), what happens to enrolled students, and what the prerequisite "tick" actually gates.

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 short sentences with the scoping constraint front-loaded and no filler. The second sentence is terse to the point of being cryptic, which is a clarity cost rather than a length problem.

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 three-parameter mutation with no output schema, the description covers the core scope but leaves key operational questions open: reversibility, effect on enrolments, and the meaning of the closed-days prerequisite. Annotations carry the safety profile, so the gap is not fatal, but it is real.

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 coverage is 100%, so id and date are fully documented in the schema, including the time-zone caveat. The description restates the oddity of passing a class id plus a date, but adds no new syntax or format information, and says nothing about the optional reason parameter. Baseline 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?

"Cancel one date of one class; the class itself is unchanged" gives a specific verb and resource and immediately scopes it against the more sweeping remove_class / remove_lesson style siblings. It stops short of naming an alternative outright, so an agent still has to infer which sibling to route to for whole-class deletion.

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 only guidance is the precondition "needs the closed-days tick at its branch," which hints at a prerequisite but is unexplained jargon. Nothing states when to prefer this over restore_lesson's counterpart, remove_class, or add_closure, and there is no when-not guidance.

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