gmail_list_labels

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

No annotations are provided, so the description carries the full burden. It clearly indicates that the operation is a read-only listing (no side effects) and adds valuable nuance by stating both system and user-created labels are included. However, it does not mention any potential limits (e.g., pagination, authorization scopes) or whether hidden labels are included, but for a list tool this is reasonably 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, succinct sentence that front-loads the verb and resource. Every word contributes meaning, with no repetition or filler. It is perfectly sized for the tool's simplicity.

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 low complexity (zero parameters) and the presence of an output schema, the description is complete. It states what is listed (all labels) and the scope (system and user-created), which is sufficient for an agent to know what to expect. The output schema can handle any return-value details, so the description need not elaborate further.

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 description coverage is 100% (empty properties). The description adds no parameter-specific details because none are needed. Baseline for zero parameters is 4, and the description appropriately says nothing beyond the tool's action.

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') with a clear resource ('Gmail labels') and explicitly scopes to 'all' including both system and user-created. This distinguishes it from sibling tools like gmail_create_label or gmail_delete_label, which are mutation operations rather than a listing operation.

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 the tool (when you need to retrieve all Gmail labels), but it does not explicitly state alternatives or exclusions. Sibling tools like gmail_list_filters serve a different purpose, yet no direct guidance is provided for choosing this over them. This is adequate but leaves the agent to infer context from the tool name and description.

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