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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile needs no restating. The description adds genuinely useful behavior beyond them: the default-to-latest behavior, the RON-per-unit direction of the rate, and the 2005 archive boundary. It doesn't describe the response shape, which is the main remaining gap.

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 short sentences, each carrying distinct information: unit and scope first, default second, data range third. No filler or restatement of the title.

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 carries the burden of explaining return values; it implies a per-currency rate mapping but doesn't state whether results come as a list, object, or single value. Otherwise complete for a two-optional-parameter read tool.

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 100%, so both the date format and the currency-code semantics are already documented in the schema. The description reinforces the unit (RON per unit) and the all-vs-one behavior, but adds no syntax or format detail beyond the schema. 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 and resource: the BNR reference exchange rate, expressed in RON per unit of currency, for either all currencies or a single one. The scope and unit are precise enough that an agent can distinguish it from every sibling (invoice, company, financials tools) without inspecting any schema.

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?

Gives the default behavior ('By default the latest published') and the data boundary ('archive starts in 2005'), which tells the agent when the tool is applicable and what range it can serve. It doesn't name a fallback or alternative, but no sibling covers exchange rates, so there is nothing to route against.

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