email_label

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 the tool mutates email state (add/remove labels) but doesn't disclose whether adding and removing can happen in one call, whether partial failures occur, what happens if a label doesn't exist, whether this is destructive/reversible, or effect on other metadata. For a mutation tool with zero annotation coverage, more disclosure is expected.

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 single-sentence description is efficient and front-loaded. It communicates the action and platform constraint without waste. However, it's arguably under-specified rather than properly concise—but for conciseness as measured here, brevity is a strength.

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?

Given 4 parameters, 0% schema coverage, no output schema, no annotations, and a mutation operation, the description is incomplete. It should at least clarify the meaning of addLabels vs removeLabels, note both can be used together or independently, and mention platform constraint implications. The description leaves the agent to infer parameter semantics from the schema titles alone.

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 description coverage is 0%, so the description must compensate. It doesn't mention any parameters: accountId, emailId, addLabels, removeLabels. The description implies the semantics of labels (add/remove via the tool name and description) but gives no specifics about which parameters map to actions or their accepted formats. This is a significant gap given four parameters, two of which are required.

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 says 'Add or remove labels on an email (Gmail only)' which clearly states the verb (add/remove), the resource (email labels), and an important platform constraint (Gmail only). It doesn't explicitly distinguish itself from siblings like email_mark or email_get_labels, but the action is reasonably clear. The 'Gmail only' qualifier adds specificity that helps differentiate from the broader email tooling.

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?

There is no guidance on when to use this tool versus alternatives like email_mark, email_move, or the batch operations. The 'Gmail only' note is the sole context clue. No exclusions, prerequisites (e.g., needing valid label names), or conditions (e.g., can both add and remove simultaneously) are mentioned.

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