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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds genuine domain behavior on top: the data is same-day only, there is no historical data, results can be compared across banks, and the buy/sell price definitions prevent misinterpretation of the returned values. It does not cover failure modes (e.g. a bank not quoting a currency) or any rate limits, which keeps it from a 5.

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?

Front-loaded with the purpose, then the when-to-use, then the parameter semantics, which is a sensible order. The closing 'The rates are of today. The tool has no history.' repeats information already implied by 'current' and 'today' earlier in the text, so a sentence of redundancy remains.

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?

An output schema exists, so return structure need not be explained, and annotations carry the safety profile. The description supplies the remaining agent-critical context: what the numbers mean (buy vs sell), which bank codes are legal, the currency-count limit, and that only today's data is available.

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 parameters are already documented, which sets the baseline at 3. The description adds real value by enumerating all fourteen valid bank codes with their full names and legal kinds (a substitute for the missing enum), but for currencies it only restates the schema's '1 to 10 ISO 4217' rule without adding format examples beyond the schema's own USD/EUR hint.

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 opening sentence gives a specific verb and resource ('Returns the current commercial exchange rates of Georgian banks') and defines the unit being priced (GEL per one unit of currency). The word 'commercial' implicitly separates it from the official-rates siblings, and 'The tool has no history' rules out the history siblings, but no sibling is named explicitly.

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?

'Use it for the price of a currency at a bank today, or to compare banks' gives a clear context for selection, and 'Ask for 1 to 10 currencies' sets the usage envelope. It stops short of explicitly naming alternatives such as rates_get_official_rates or rates_list_official_history, so the agent must infer that official/central-bank rates belong elsewhere.

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