list_email_labels

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

No annotations are provided, so the description carries the behavioral disclosure burden. 'Retrieve' clearly signals a read-only operation, and 'all available' scopes the result, but the description does not mention authentication needs, rate limits, or whether system labels are included. The output schema covers return shape, which keeps this acceptable but not rich.

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, front-loaded sentence with no filler. Every word contributes directly to understanding the tool's function.

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 zero-parameter, read-only listing tool with an output schema, this description is sufficient. An agent can understand exactly what action will be taken and what the result will relate to, and the output schema is expected to resolve any remaining details about return structure.

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 zero parameters, and the input schema fully documents that fact. The rubric baseline for zero parameters is 4, and there is nothing further the description needs to add about parameter semantics.

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 ('Retrieve') and a clear resource ('all available Gmail labels'), making the tool's purpose immediately obvious. It is also easily distinguished from sibling label mutation tools like create_label, update_label, and delete_label.

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 the tool is for fetching the complete set of Gmail labels, but it gives no explicit guidance on when to use it versus alternatives. For a zero-parameter list operation this is a minor gap, so it earns an implied-usage score rather than a higher one.

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