list-i18n-languages

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

The description discloses that the tool 'Costs 1 quota unit per call,' which is useful behavioral information beyond the schema. Since no annotations are provided, this adds some transparency about cost/rate implications, though it does not describe return format or any other side effects.

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 a single sentence that provides the essential purpose and a key behavioral detail (quota cost). Every word contributes to understanding; there is no redundancy or filler.

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?

Given the simplicity of the tool (no parameters, no output schema, no annotations), the description is sufficient for an agent to understand its core function. However, it does not describe the format or contents of the returned language list, which would be helpful since no output schema exists.

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 has 0 parameters, so the schema leaves nothing to explain. Per the rubric, a 0-parameter tool gets a baseline of 4. The description correctly focuses on the operation rather than inventing parameter details.

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 uses a specific verb ('List') and a clear resource ('the application languages supported by YouTube'), making the purpose immediately obvious. It also distinguishes from the sibling tool list-i18n-regions by specifying 'application languages' rather than regions.

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?

The description implies usage (when you need to list supported application languages) but provides no explicit guidance on when to use this tool versus alternatives, no prerequisites, and no exclusions. The mention of quota cost is a partial usage consideration but not a substitute for usage guidance.

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