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

No annotations are present, so the description carries the full burden. It adds useful traits: rates are official, daily, refreshed once per day, and the tool costs $0.008 USDC. However, it does not disclose whether the call is read-only, what the response contains, or how missing or delayed rates are handled.

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?

The description is one dense sentence that front-loads the core resource and update behavior, then adds scope and pricing. Every part earns its place and there is no filler.

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?

Given the opaque schema and absence of an output schema, the description is not sufficient for reliable invocation: an agent still cannot tell how to construct the required `args` and `extra` objects or what the return value looks like. The update cadence and pricing are useful, but too much essential context is missing.

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?

The input schema is opaque, with generic `args` and `extra` objects and 0% schema description coverage. The description adds domain knowledge by listing currency codes and mentioning ISO codes, but it never maps those codes to the required `args`/`extra` structure or explains what `extra` is for.

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 identifies a concrete resource: official Central Bank of Russia exchange rates, with specific currency examples and ISO codes. It lacks an explicit verb like 'get' or 'list,' but the noun phrase is unambiguous and distinct from siblings such as moex_quote.

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 description implies this is the tool for daily official CBR FX rates for USD, EUR, CNY, GBP, KZT, and other ISO codes. It does not explicitly state when not to use it or compare it to alternatives, despite moex_quote being a plausible sibling for market data.

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