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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description usefully adds that a "/" in the name produces a nested label, but it omits duplicate-name behavior, idempotency, and the fact that creating a label does not apply it to any messages.

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 short sentences with zero filler, and the core action is front-loaded ahead of the optional nesting syntax detail.

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?

With no output schema and annotations covering safety, the description supplies the one non-obvious input behavior (nested naming). It is nearly complete for a two-parameter creation tool, lacking only duplicate-handling guidance.

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?

Schema coverage is only 50% (mailbox is documented, name is not), so the description must compensate for the gap. It does so by defining the naming syntax for nested labels, though it adds nothing about length limits or reserved names.

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?

States a specific verb and resource ("Create a new Gmail label"), which cleanly separates it from rename_gmail_label, delete_gmail_label, and list_gmail_labels. It does not, however, explicitly name or contrast itself with a sibling, so it falls short of a 5.

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 creation intent is implied by the name and description, but there is no when-to-use/when-not guidance: nothing about what to do if the label already exists (find_duplicate_gmail_labels / merge_duplicate_gmail_labels exist) or the difference between creating a label and applying it via apply_gmail_labels.

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