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

The description asserts non-mutating behavior — answers are not returned and are not marked as viewed — yet the annotations declare readOnlyHint=false and idempotentHint=false. For a pure counting operation these conflict, so the definition directly contradicts its own structured safety profile.

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?

Three tight sentences, front-loaded with what is counted and where, then the no-side-effect note, then the tariff prerequisite — no filler. The tariff sentence is slightly terse ('Нужна опция фильтров результатов в тарифе'), but nothing is wasted.

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?

With no output schema, the description should say what comes back (a number? an object?), and it does not. It covers purpose, side effects and a prerequisite well, but leaves the return value and any behavior on large filtered sets unspecified.

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%; the schema already documents quiz_id, section (with the report=statuses / answers=is_complete,is_screenout,is_deleted,search mapping) and the nested filters object. The description only restates that filters are passed, adding nothing beyond the schema, so the 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?

States a specific verb+resource (counts answers) and scopes it to the two sections, report vs. the «Ответы» list, with the given filters. It implicitly separates itself from the fetching siblings by saying it does not select the answers themselves, but never names an alternative tool (e.g. get_quiz_answers) explicitly, so it falls just short of a 5.

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?

Makes the use case clear (get a total instead of the answers) and adds a real prerequisite: the results-filter option must be enabled in the tariff plan. It stops short of stating explicit when-not conditions or naming sibling alternatives to route against.

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