gmail_list_labels

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

With no annotations provided, the description carries the full burden. It adds behavioral transparency by explicitly stating that system labels are included ('system and user-created'), which clarifies the scope beyond a generic 'list labels' command. However, it does not mention return format or pagination, but these are likely covered by the output schema.

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, terse sentence that immediately states the action and scope. It is front-loaded and every word contributes meaning, with 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?

For a simple listing tool with no parameters and an output schema, the description is complete. It specifies the full scope (all labels, including system-created), which is the primary contextual information an agent needs. The presence of an output schema covers return-value details, so no further description is necessary.

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, so the baseline is 4. The description correctly avoids adding unnecessary parameter details and instead focuses on the output behavior, which 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 clearly states the action (list) and resource (Gmail labels) with the specific scope of 'all' labels, including both system and user-created. This distinguishes it from sibling tools that create, delete, or modify labels, making the purpose unambiguous.

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 when to use this tool: whenever you need a complete enumeration of Gmail labels. It provides clear context by specifying that both system and user labels are included, but does not explicitly mention exclusions or alternatives. Given that there is no alternative listing tool in siblings, the implicit guidance is sufficient.

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