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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description's one genuine addition is the 366-day range cap, which is non-obvious. It says nothing about which rate source/provider is used, which is the key behavioral distinction from kurs_bi_history.

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?

One front-loaded sentence with no filler and the constraint placed where it will be read. It is efficient, though it spends its single sentence without addressing the provider ambiguity.

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 four parameters, a 50% schema coverage, and no output schema, the description needs to carry more weight. It omits the rate source and the expected currency-code format, leaving real gaps an agent would have to guess at.

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 only 50%: base and target have no descriptions at all. The phrase 'currency pair' loosely implies those two parameters but gives no format, accepted values, or default behavior, so the description fails to compensate for the coverage gap.

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 and resource (get historical exchange rates) plus the scope (currency pair over a date range), which an agent can distinguish from kurs_latest. It does not, however, differentiate itself from the closely named sibling kurs_bi_history.

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 word 'historical' implies usage, but there is no explicit when-to-use statement and no named alternative. An agent choosing between this, kurs_latest, and kurs_bi_history gets no routing help.

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