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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and external-dependency profile is covered. The description usefully specifies that results are deal-basis plus telegraphic buying/selling rates, which tells the agent what the payload contains. It says nothing about freshness, default date behavior, or the upstream API's rate limits.

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?

A single front-loaded sentence with no filler; the source and the data content are stated up front. It is arguably too terse for a data-retrieval tool, but nothing in it 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 and a half-documented parameter set, the description carries the burden of explaining defaults and return shape. It never says what happens with no arguments (both params optional), how the date is formatted, or whether results are a time series or a single snapshot.

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%: ccy is documented as comma-separated ISO codes, but date has no description in the schema and none in the tool description either. With both parameters optional (0 required), the agent gets no explanation of what happens when date is omitted or what format date accepts.

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 names a specific resource (KRW exchange rates), its authoritative source (Export-Import Bank of Korea), and the exact rate types returned, so the agent knows precisely what data this yields. It does not distinguish itself from the sibling kr_rates, so an agent cannot tell from text alone which of the two rate tools to pick.

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?

There is no when-to-use guidance, no prerequisites, and no mention of the obvious alternative (kr_rates) despite it being a sibling. The agent must infer selection purely from the resource name.

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