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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered structurally. The description adds limited extra value by noting results carry source attribution and dates, but says nothing about update cadence, freshness, or geographic coverage behavior. With annotations carrying the main burden, a 3 fits.

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?

A single tight sentence with no padding, and the most informative content (source attribution, dates) is up front. It is a noun-phrase fragment rather than a full statement of behavior, which keeps it from a 5.

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 two parameters, an enum plus default, and no output schema, the description should clarify how region and countryCode interact and what geographic granularity is returned. It only gestures at return content ('source attribution and dates') and leaves all parameter behavior unstated, which is inadequate for a filtering-based 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 description coverage is 0% and neither parameter is mentioned in the description. The agent gets no explanation of what 'region' means, that it defaults to 'europe' vs 'ukraine', or how countryCode relates to region, yet geographic scoping is the core behavior of this tool.

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 a specific resource ('fuel prices') with meaningful qualifiers ('average', 'source attribution and dates'), which separates it from sibling price tools like get_green_card_price and get_oscpv_price. The operation verb ('get') is only implied, and it does not explicitly state how it differs from those siblings, so it stops short of a 5.

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?

There is no when-to-use, when-not-to-use, or alternative-tool guidance anywhere in the description. It never mentions that region/countryCode scoping selects this tool over the other price endpoints, leaving the agent to guess based on the name alone.

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