list_labels

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

No annotations are provided, so the description carries the burden. 'List all' clearly signals a read-only operation with no mutation or side effects, and 'with their ids' hints at the returned data. It does not detail pagination or response encoding, but for a zero-parameter list operation this is a minor omission.

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 filler. Every word contributes to the tool's purpose and output, making it immediately scannable for an agent.

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 tool's simplicity—no parameters, no output schema, minimal annotations—the description is nearly complete: it names the resource, the operation, and the returned fields. It could add a little more context about Gmail account scope or the exact response shape, but these are minor given the trivial interface.

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 there is nothing for the description to add beyond the input schema. This matches the baseline for parameterless tools, and the description accurately reflects that no inputs are needed.

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 resource ('Gmail labels'), and specifies the returned data ('with their ids'). This clearly distinguishes it from the sibling message-focused tools such as search_messages and get_message, as well as from modify_labels, which performs a different action.

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 intended use is implied: use this tool when you need all Gmail labels or their IDs, possibly before calling modify_labels. However, it does not explicitly state when to prefer this over alternatives or exclude cases where it should not be used.

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