list_labels

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

With no annotations, the description must convey behavioral expectations. 'List' clearly indicates a read-only operation with no destructive side effects, and 'all' sets an expectation of complete label/folder enumeration. It does not mention response format or system labels, but for a simple read-only tool the core behavior is transparent.

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 wasted words. It states exactly what the tool does without redundancy.

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 tool without an output schema, the description adequately communicates the return concept: all Gmail labels and folders. It falls slightly short of 5 by not mentioning whether system labels are included, the response shape, or how the results relate to sibling tools like get_emails_by_label.

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 schema is fully covered as an empty object. Since there is nothing for the description to add about parameter usage, the baseline score of 4 is appropriate.

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 clear verb ('List') and specifies the resource ('all Gmail labels and folders'). It fully describes the tool's function and is easily distinguished from sibling email- and label-manipulation tools.

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?

No guidance is provided on when to use this tool versus alternatives such as get_emails_by_label. The description does not mention prerequisites, exclusions, or the natural workflow of first listing labels and then using them to filter emails.

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