Ключевая ставка ЦБ РФ

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the 'Только чтение' clause is largely duplicative. It does add one useful non-annotation fact ('без токена' – no auth token required), but does not disclose pagination, rate limits, or error behavior on malformed dates.

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 compact sentences, front-loaded with the resource and returned fields, followed by use cases and an operational note. Every sentence is short and earns its place, though the use-case clause is the weakest link.

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?

There is no output schema, so the description correctly takes on the return-value burden by naming current value, last-change date, and history. Both optional params and the read-only/no-token profile are covered, leaving only sibling disambiguation and edge-case handling unaddressed.

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%, with both 'from'/'to' documented, including their defaults, so the schema already carries the semantics. The description restates the default 2-year period but adds no format or boundary guidance beyond what the schema provides – baseline 3.

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 resource (Банка России ключевая ставка) and precisely what it returns: current value, last-change date, and period history. The purpose is unambiguous. However, it fails to differentiate from the sibling cbr_rate_history, which it likely overlaps with since it also returns history for a period.

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?

It gives scenario context ('пригодится для расчёта пеней, процентов по ст. 395 ГК и оценки стоимости денег'), which implies when to reach for it. But it never names the alternative siblings (cbr_rate_history, cbr_rates, late_payment_penalty) or states when this tool is the wrong choice, leaving the routing ambiguity unresolved.

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