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

Goes well beyond the annotations (which only cover read-only/idempotent/non-destructive) by disclosing cost (0 credits), that calls work without an API key but are rate-limited per IP, data provenance (BNR, values unchanged from source), and the 366-day range ceiling. These are exactly the operational facts an agent cannot infer from structured fields.

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 chains resource, units, tenors, query modes and limits without filler. It is dense — semicolon-separated clauses rather than bullets — but every clause carries information an agent needs.

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, and the description does not state the return shape (e.g. date plus ROBOR/ROBID columns, or how a series is ordered), which is the main missing piece for a data-retrieval tool with zero required params. Coverage of range, cost, auth and provenance is otherwise strong.

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 25% (only 'tenor' is documented), so the description must compensate, and it largely does: it enumerates the allowed tenors, explains that 'date' yields the latest fixing on/before, that from/to define a series, and that the window is capped at 366 days. It does not clarify whether both ROBOR and ROBID are returned together or how tenor interacts with the single-date mode, leaving a small 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?

Names the exact resource (ROBOR offered / ROBID bid fixings), units (% p.a.), coverage start (1995-08-01) and the two supported query shapes. It is clearly separable from get_bnr_exchange_rate and get_ircc by subject matter, though it never explicitly contrasts itself with those closely related Romanian-rate siblings.

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?

Explicitly states the two usage modes and their conditions: a single 'date' returns the latest fixing on or before that date, while 'from'/'to' returns a series for one tenor capped at 366 days. It also flags the free/keyless path, giving the agent enough to choose a call shape, but gives no exclusions or guidance on when another tool (e.g. get_ircc) is preferable.

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