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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, so the description is not carrying the safety burden. It adds genuinely non-obvious behavior: prices are today-only with no history, prices are per unit with explicit units per grade, and a missing self_service_price means the company offers no self-service product. The repeated "publishes no effective date" notes hint at a data-quality caveat but never say how it affects the returned prices, which keeps this 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 core action and scope, then layered into product/price semantics and company codes. It is on the long side and repeats the eight grade names already present in the schema, plus the "publishes no effective date" parenthetical seven times, but each sentence still carries information.

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 an output schema present, the description need not explain return shape, and it covers the remaining agent questions: units, today-only freshness, the meaning of a missing self-service price, and the valid company codes. The unexplained "no effective date" caveat is the one loose end for a tool this data-centric.

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% and the schema already documents grades, default language, and empty-array-means-all behavior, so the baseline is 3. The description does add real value by enumerating the eight company codes with their display names, which the schema only gestures at ("The description of the tool lists the codes"), but the grade and language semantics are pure restatement.

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 names a specific verb and resource ("Returns the current fuel prices of Georgian fuel companies") and immediately pins down the unit (GEL per unit of product). It is unambiguous against every sibling in the list (rates, transit, stats, etc.), none of which touch fuel.

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?

It gives concrete use cases (price of petrol/diesel/gas at a company today, or comparing companies) and rules out the biggest misuse with "The tool has no history." The only gap is that no sibling or alternative is named for historical or other-currency lookups, but the scope statement is strong enough that an agent will not wander.

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