gmail_apply_labels_to_messages

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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It fails to mention side effects, permission requirements, idempotency, or behavior for missing labels. Only the basic action and query restriction are stated.

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 extremely concise, consisting of two short sentences with no redundant information. The key details are front-loaded.

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 the tool mutates state with 5 parameters and no output schema, the description is too minimal. It lacks details on return values, effect on labels, and how parameters interact, making it incomplete for an agent to use 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?

Schema description coverage is low (40%), and the description does not compensate. It does not explain the add_label_names, remove_label_names, or create_missing_labels parameters beyond the general action, leaving their semantics unclear.

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 tool applies or removes Gmail labels on explicit message IDs. It distinguishes from query-based tools by explicitly saying 'Does not accept queries.', making the purpose unambiguous.

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 description indicates the tool should not be used with queries, providing a usage constraint. However, it does not explicitly name alternatives like gmail_search_messages or gmail_prepare_bulk_label_query, leaving the agent to infer when to use this vs. siblings.

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