gmail_modify_labels

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

With no annotations, the description carries the full burden. It discloses key behaviors like removing INBOX archives a message and adding STARRED stars it, providing concrete side effects. However, it does not mention persistence, permission requirements, or response details, though 'modify' implies a write operation.

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 two sentences, front-loaded with the primary purpose, and uses concise, meaningful examples. Every word earns its place with no filler.

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?

The tool is moderately simple, and an output schema exists (signaled by context), so return values do not need explanation. The description covers main use cases and distinguishes itself from sibling tools. It could be more complete by mentioning that multiple labels can be added/removed simultaneously or that message_id is required, but the provided examples give sufficient coverage.

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 0%, requiring the description to compensate. It provides example values (INBOX, UNREAD, STARRED) that map to add_labels and remove_labels, but it does not explicitly describe parameters by name or explain the array semantics fully. The required message_id is not referenced in the description at all.

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 states 'Modify labels on a message' with a specific verb (modify) and resource (message), clearly distinguishing it from sibling tools like gmail_create_label or gmail_delete_label. The examples (archive, mark read, star) further clarify the exact actions performed.

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 explicitly says 'Use to archive, mark read, star, etc.', providing clear contexts for when to apply the tool. It lacks explicit alternatives or 'when not to use' guidance, but the examples serve as a strong usage guide.

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