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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open world), and the description adds genuinely non-obvious behavior: publication around 17:00 Tbilisi, effect from the next day until the next set, and that a weekend or holiday returns the set in force. The caveat that the official rate is indicative and not a bank price further prevents misinterpretation of results.

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?

Purpose is front-loaded, followed by usage contexts then behavioral timing notes — a sensible order with no filler sentences. Minor overhead comes from explaining output fields ('quantity' units vs `rate_per_unit`) that an output schema already covers.

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 annotations, a full output schema, and 100% parameter coverage already present, the description supplies exactly the missing operational context: publishing schedule, effective dates, and holiday behavior. Only edge-case error handling for out-of-range dates is left implicit in the schema text.

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 description coverage is 100%, so date bounds, the en/ka language choice, and the ISO 4217 currency list with a 50-item cap are already fully documented in the schema. The description adds no parameter-level detail (e.g., no guidance on combining currencies with an empty date beyond what the schema states), so the 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?

The first sentence names a specific verb and resource ('Returns the official exchange rates of the lari ... for one date'), giving a precise read operation with a single-date scope. It also conceptually separates itself from commercial/bank pricing ('It is not the price of a bank'), though it never names the sibling tool rates_get_commercial_rates or rates_list_official_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 description supplies concrete use contexts ('the rate of a currency today or on a past date, for a contract, an invoice, or a tax form'), which tells an agent when this tool is appropriate. It stops short of excluding alternatives — nothing says to use rates_get_commercial_rates for bank pricing or rates_list_official_history for ranges.

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