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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds a genuinely new behavioral fact not in the annotations: the call is free and spends no credits, which matters in a paid API ecosystem. It does not describe the shape or volume of the returned feature list, 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?

Three short sentences and zero filler. The purpose comes first, the usage guidance second, and the cost note last where it functions as a justification for using the tool.

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?

For a simple read-only discovery tool with three optional parameters and no output schema, the description covers what it does, when to call it, and that it is free. The only gap is that it does not indicate what form the feature list takes, though with a list-shaped tool that is a minor omission.

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 the schema already documents store, country, and language, including the enum values and ISO format. The description only echoes store and country and never mentions the language parameter or how it affects returned names. With the schema doing the heavy lifting, 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?

States a specific verb and resource with scope: 'List which parts of the dataset are available for a store and country.' That is concrete and clearly distinct from sibling tools like list_categories, list_countries, and list_tools by virtue of the store/country scoping. It stops short of explicitly contrasting itself with those siblings, so 4 rather than 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?

Gives an explicit usage context: check whether a kind of data exists for a market before spending credits. That is a clear when-to-use recommendation tied to a cost tradeoff. It names no alternative tool or explicit exclusion, so it sits at 4.

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