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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is fully covered structurally. The description's only added behavioral context is the usage-based billing note with a $0.012 estimate, which is genuinely useful but does not address freshness, caching, or result scope.

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 functional sentence is short, front-loaded, and free of waste. The appended pricing block is boilerplate but clearly demarcated and does not obscure the core statement.

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?

An output schema exists, so return-value explanation is unnecessary, and with no parameters the description is nearly sufficient. It still lacks any hint of how this language list relates to the parallel locales/locations lookup tools, leaving the agent to guess which reference endpoint to call.

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 per the rubric the baseline is 4. There is nothing for the description to clarify beyond confirming the call is argument-free.

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 clear verb (receive) and specific resource (list of languages supported by Bing Ads API), so an agent knows exactly what it returns. However, it offers no differentiation from the many sibling reference-list tools such as get_dataforseo_keywords_bing_kw_for_url_languages, get_dataforseo_keywords_bing_locations, or the various *_locales tools, which all return lookup lists.

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: as a no-parameter lookup of supported languages, an agent can infer it is called to validate or enumerate language codes before issuing a Bing keywords request. There is no explicit when/when-not guidance and no mention of which sibling lookup (locales, locations, kw_for_url_languages) to prefer for a given need.

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