Modify email labels

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that labels can be added or removed, but offers no information about required permissions, side effects (e.g., whether removing UNREAD marks the message as read), idempotency, or failure behavior. This is a significant gap for a mutation tool.

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 concise sentence with no filler. It is appropriately short for the tool's simplicity, though it sacrifices some helpful detail for brevity.

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 tool with no annotations and no output schema, this description leaves important gaps. It does not specify when to use it over sibling tools, what happens after the operation, or any prerequisites. Given the simplicity of the tool and complete schema, it is minimally adequate but incomplete.

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 schema provides 100% coverage, describing all four parameters with clear types. The description adds some semantic value by giving examples of label values (STARRED, UNREAD, etc.), which helps an agent infer valid inputs, but it does not explain the relationship between addLabels/removeLabels and these examples beyond 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 description clearly states the action ('add or remove labels') and the resource ('a message'), with concrete examples that make its scope understandable. It does not explicitly differentiate from sibling tools like google_gmail_trash or google_gmail_untrash, but the label-oriented framing is distinct 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?

No guidance is given about when to use this tool versus alternatives. For example, it does not mention that google_gmail_trash and google_gmail_untrash should be used for trash-specific operations, or that google_gmail_labels_* tools manage labels themselves rather than applying them to messages.

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