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

No annotations are provided, so the description carries the full disclosure burden. It reveals one useful behavior — that '/' in the name creates nested labels — but omits other traits an agent would want for a create operation: behavior on duplicate label names, whether the created label ID is returned, and any label-count limits. The description is not misleading, but it is thin on behavioral detail.

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 with no filler: the core action is front-loaded, and the nested-label rule earns its place immediately after. The example is compact and concrete rather than verbose.

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 two-parameter tool with no output schema and no annotations, the description covers the central operation and the main format nuance, while the schema handles mailbox selection. However, it never states what response to expect (e.g., created label ID) or how duplicate labels are handled, which matters for follow-up workflows like apply_gmail_labels. It is adequate but leaves clear gaps.

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 50%: the mailbox parameter is well-documented in the schema (email format plus a pointer to list_authorized_mailboxes), while name has no schema description. The description compensates for the name gap by teaching the slash convention for nested labels with a concrete example. This adds real meaning beyond the bare string type in the schema.

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 first sentence names a specific verb and resource ('Create a new Gmail label'), so an agent can tell this is a create operation on Gmail labels rather than mail folders or other resources. The slash-nesting tip further clarifies what a label name means. It doesn't explicitly contrast with sibling tools like rename_gmail_label, delete_gmail_label, or apply_gmail_labels, but the verb+resource pairing is unambiguous enough.

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 nested-label example ('Clients/Acme') provides a how-to hint but no guidance on when to choose this tool over alternatives such as create_mail_folder, apply_gmail_labels, or rename_gmail_label. There are no when/when-not conditions or exclusions. Given the large sibling set of label- and folder-related tools, an agent gets little routing help from the description.

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