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

The annotations already declare readOnly=true, openWorld=false and non-destructive, so the safety profile is covered. The description adds real value by enumerating the three verdicts (found, no_such_class, not_out_yet) and explaining that not_out_yet means the month isn't published yet, but it says nothing about what the response shape looks like or how unknown branches/levels are reported.

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 sentences, front-loaded with the core capability and followed by the verdict vocabulary. The 'the way the public page and the business's assistant do' clause is slightly indirect but earns its place by conveying expected output parity.

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 read-only lookup with no output schema, the description does the heavy lifting on returns: it lists next lessons, places left, trial availability and the three verdicts. The remaining gap is that all four parameters are optional, and the description never says what happens with no arguments — whether it answers across all branches or requires at least a level.

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 all four parameters (level, month, branch, subject) are already documented including the month pattern and its 'this month' default. The description only reinforces that these are the filtering axes and that an unpublished month yields not_out_yet — helpful but marginal over the schema.

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 gives a specific verb ('answer') and a precisely scoped resource: which classes take a level/subject at a branch in a month, plus next lessons, places left and trial availability. That composite-answer framing implicitly separates it from the list_* siblings, though it never names one, so an agent must infer the distinction rather than being told.

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 clearly framed as 'answer a family's question the way the public page and the business's assistant do', which tells the agent the context and expected parity with the public site. There are no explicit exclusions or named alternatives (list_classes, list_branch_lessons), so the agent gets strong context but no routing rules.

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