categories-list

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. The verb 'List' makes the read-only nature clear, and the description states what the tool returns ('IDs and descriptions'). For a simple listing operation, this is sufficient transparency.

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, focused sentence that front-loads the action and resource. Every word adds useful information: 'Gmail', 'category labels', 'CATEGORY_*', 'IDs', and 'descriptions'.

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?

This is a low-complexity, zero-parameter read-only listing tool with an output schema available. The description fully explains what the tool returns and which labels it covers, leaving no critical gap for an agent to successfully select and invoke it.

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 is empty, so there are no parameter semantics to document. The description does not need to compensate for schema gaps, and the baseline for zero-parameter tools is appropriately 4.

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 identifies the exact resource ('Gmail category labels (CATEGORY_*)') plus the returned fields ('IDs and descriptions'). This clearly distinguishes it from sibling tools like labels-list, which handle user-created labels rather than Gmail's built-in CATEGORY_* labels.

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 provides clear context by specifying that this tool handles Gmail category labels, not ordinary labels. It does not explicitly name alternatives or state when not to use it, but the CATEGORY_* qualifier makes the intended use unambiguous.

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