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

Annotations already provide readOnlyHint=true, so the description correctly does not contradict them. The description adds behavioral context by explaining the semantic difference between detected language and locale, and states the ordering basis ('ranked by occurrence count'). This goes beyond the annotation data and helps the agent understand the tool's behavior.

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 concise: three sentences, each meaningful. The first sentence states the core purpose, the second clarifies the distinction from a sibling, and the third gives a practical use case. There is no redundant or filler content, and the key differentiating information is front-loaded.

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?

The tool has two optional parameters, full schema documentation, an output schema, and readOnly annotations. The description provides enough conceptual clarity for selection and invocation, and the existing structured metadata covers parameter details and safety. Nothing critical is missing for an agent to correctly use this 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 100%, as both limit and time_filter have detailed descriptions with defaults and constraints. The tool description does not need to add parameter-specific semantics; the baseline of 3 applies because the schema already carries the burden and the description adds no extra parameter insight.

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 clearly states that the tool returns top detected natural languages of user CHAT questions ranked by occurrence count. It also explicitly differentiates from get_top_locales by explaining the conceptual distinction between detected language and locale, making the tool's purpose specific and distinguishable from siblings.

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 explicitly names get_top_locales as the alternative and explains the key difference: locale reflects embed/browser setting, while language is detected from actual query text. The description also provides a concrete use case ('spot mismaches e.g. German-speaking users hitting an English-only embed'), giving clear guidance on when and why to use the tool.

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