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

No annotations exist, so the description carries the full behavioral burden. The verb 'Return' implies a read-only operation, but the description does not disclose what happens when the country parameter is omitted, what the response structure looks like, or that the listed countries are a subset of the schema's enum. The mismatch between 'UK' in the description and 'GB' in the schema is misleading.

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?

The description is a single sentence with the core action front-loaded)Skip the parenthetical country list, which is not only unnecessary but adds noise and inaccuracies. Padding aside, the structure is appropriately concise.

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?

This is a simple tool with one optional parameter and no output schema, so the description should explain the omission behavior and return shape. It does neither. Without any annotation and with ambiguous relationships to sibling feature tools, the definition is incomplete for an agent to invoke it with confidence.

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 the schema already documents the parameter clearly, including the 'Omit for the full matrix' instruction. The description adds a parenthetical list of countries that is incomplete and uses 'UK' instead of the ISO code 'GB', which could lead an agent to pass a non-enum value. This adds misleading rather than helpful meaning.

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 description uses a specific verb-resource pair ('Return features available per supported country') that clearly indicates the tool's function. It does not, however, differentiate itself from sibling tools like list_features or feature_search, and the parenthetical country list conflicts with the much larger schema enum, slightly muddying the scope.

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 guidance on when to use this tool versus alternatives such as list_features, feature_search, or compliance_capabilities. The description does not state exclusions or conditions like 'use this when you need feature availability for a specific country'.

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