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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds only the underlying endpoint (GET /v2/gl), which is mild context and does not disclose return shape or sizing.

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 terse fragments with the key information front-loaded and zero filler. Nothing is wasted for a simple reference 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 zero-param list endpoint with no output schema, the description conveys what is returned and how it is used. It would be stronger with a note on the return format (e.g., list of code/name pairs), but it is adequate.

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?

With zero parameters, the baseline is 4. The description does tie the output to the 'gl' parameter semantics, adding useful meaning about how the returned codes are consumed, though it gives no example values or format.

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 states a specific resource (supported country codes) and its role (values for gl). It is distinguishable from sibling zenserp_list_languages, though it relies on the title for the 'list' framing rather than a verb in the description itself.

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?

Usage is implied: these are the values to feed into the 'gl' parameter of the search tools. However, there is no explicit statement of when to call this versus looking values up elsewhere, and no mention of related siblings like list_languages.

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