gmail_list_labels

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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond those annotations by stating the tool returns every label and that the id field is the important part for downstream filing tools. This is a concise disclosure of scope and output emphasis.

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?

Two sentences, both purposeful. The first states the output clearly, and the second explains why that output matters. No filler, no redundancy, and the most important information is front-loaded.

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 parameterless listing tool with an output schema and comprehensive annotations, this description is fully sufficient. An agent knows what it will get, why to use it, and that it is safe to call. Nothing essential is missing.

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 100% schema description coverage, so the baseline is 4. The description adds no parameter detail because none is needed, but it does clarify the semantic role of the returned id, which is the only meaningful data an agent will consume.

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 identifies the resource (labels) and the output (each label with its id), and the name reinforces the action. It does not use an explicit verb like 'lists', but 'Every label, with its id' is unambiguous. It also subtly distinguishes this tool from label-modifying siblings by pointing to label ids as the input for filing 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?

The phrase 'Label ids are what the filing tools take' signals exactly when this tool is useful: before performing filing operations that require label ids. It does not offer explicit exclusions or alternatives, but no competing list-labels sibling exists, so the practical usage context is clear.

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