list_labels

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description still adds real value by explaining that system labels map to folders while STARRED and UNREAD are flags, preventing misinterpretation of returned ids. It stops short of noting whether system labels are mutable or how counts are computed.

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?

Four short sentences, front-loaded with the purpose, then domain semantics, then the follow-up action. Dense and waste-free, though the folder-mapping sentence is long and could be tightened.

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, the description carries the return-value burden and does so by naming the fields (id, message count, unread count) and referencing them downstream. It leaves minor gaps such as ordering or whether nested/user-label hierarchy is returned.

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 takes zero parameters, so the baseline is 4; the description correctly implies an unfiltered, account-wide listing without inventing parameter distinctions.

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 ("Lists labels") plus the payload returned (message and unread counts), which distinguishes it cleanly from the sibling mutators create_label/update_label/delete_label. The Naver-Mail folder semantics further pin down what a "label" is in this domain.

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?

"Use the returned id with label tools" explicitly positions this as the discovery step preceding label_message/label_thread/update_label etc. No exclusion guidance is given (e.g., when to skip listing), so it falls short of a 5.

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