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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds genuinely useful billing context (default estimate $0.012 USD, not a fixed price), which is value beyond the annotations, but it discloses nothing about response shape or pagination.

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 core purpose sentence is appropriately short and front-loaded, but the definition is padded with an injected zero-width character and a pricing HTML-comment block that, while informative, is boilerplate rather than tool-specific guidance.

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 no-parameter metadata-listing endpoint with an output schema present, the definition covers what is needed; return-value explanation is unnecessary since the output schema carries it. Only sibling differentiation is absent.

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?

The tool takes zero parameters, so the schema has nothing to describe and the baseline is 4. No parameter meaning is needed or missing.

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 clearly: retrieve the full list of locations and languages supported in the AI Keyword Data API. However, it does not distinguish itself from the similar sibling get_dataforseo_ai_llm_mentions_locales, leaving the agent to infer which locale list applies to which API.

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 only implied: this is a metadata endpoint presumably called before issuing AI Keyword queries to discover valid locations/languages. No explicit when-to-use or when-not guidance is given relative to the sibling locales tool.

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