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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is fully covered externally. The description adds nothing beyond that — no note on whether the result set is stable, paginated, or cached, and no auth or rate-limit context. It restates the outcome without enriching it.

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?

A single compact sentence with the resource front-loaded. The 'By calling this API you will receive' framing is slightly wordy boilerplate, but nothing is padded or repeated.

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 read whose output schema already documents the return shape, the minimal description is nearly adequate. What is missing is any hint of how the returned languages are meant to be consumed in the keywords workflow, which the sibling set makes relevant.

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-side burden is nil; per the rubric a 0-parameter tool has a baseline of 4. The description correctly implies no input filtering is needed to enumerate the language list.

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 names a specific resource (the list of languages supported by the Bing Ads API) and makes clear the tool is a read-only enumerator, which distinguishes it from sibling lookups like _locations or _locales. It stops short of explicitly contrasting itself with those near-neighbors, so it falls just below the top tier.

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 statement of when to call this versus the many sibling lookup tools (e.g. get_dataforseo_keywords_bing_locations, get_dataforseo_keywords_bing_kw_performance_locales), nor any prerequisite or follow-on context. Usage is only implied by the phrase 'By calling this API you will receive'.

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