gmail_list_labels

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

Annotations already cover the safe, read-only, idempotent nature of the tool. The description adds useful behavioral details beyond that: it returns a JSON list rather than a single object, and it includes both system and user-created labels rather than only user-defined ones.

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 compact and front-loaded, with a clear scope statement followed by a concise return format. There is no filler or redundant restatement of the tool name.

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 simple, no-argument listing operation, the description covers scope and return shape, while annotations cover safety and idempotence. Nothing essential is missing for an agent to invoke this tool correctly.

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 input schema has no actual parameters apart from an empty required 'params' wrapper, so there are zero meaningful parameters to document. The baseline of 4 applies because the schema is self-explanatory and no parameter-level description is necessary.

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 opens with a specific verb and resource: 'List all Gmail labels', and adds meaningful scope by noting both system labels like INBOX and user-created ones. This clearly distinguishes it from sibling tools that operate on messages, drafts, calendars, or drives.

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 usage is strongly implied: use this tool when you need the full set of Gmail label IDs/names/types. There is no sibling tool for listing labels, so an explicit alternative is unnecessary, though the description stops short of stating exactly when an agent should prefer this over other Gmail operations.

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