Copy email

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

The annotations indicate readOnly=false, idempotent=false, and destructive=false, which are informative. The description goes slightly beyond by asserting the operation is a 'copy' (implying non-destructive) and scoping to 'same account,' but it does not mention potential side effects like creating a new message ID or retaining original flags. It lacks explicit behavioral details.

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—two short sentences that convey the action, scope, and a key reference for obtaining an ID. There is no redundant wording or extraneous information, making it easy to parse quickly.

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 tool with no output schema and only two parameters, the description covers the essential context: what it does, where to get the destination ID, and the account scope. It lacks minor details like whether the operation is synchronous or how to handle errors, but these are not critical for a basic copy action. The absence of an output schema reduces the need for return-value explanation.

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 lists two string parameters, messageId and destinationMailboxId, with no descriptions (schema coverage 0%). The description partially compensates by explaining that the destination id comes from list_mailboxes, but it does not clarify what messageId refers to (e.g., the source email ID, format, or how to obtain it). Thus, only half of the parameters receive contextual guidance.

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's function: 'copy one message to a mailbox in the same account.' The verb 'copy' and object 'message' are specific, and the phrase 'in the same account' adds relevant scope. It also distinguishes this tool from siblings like mail_move and mail_trash by focusing on the copy action.

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 tells the user to 'Use this to copy one message' and provides the crucial pointer: 'Obtain the opaque destination id from list_mailboxes.' This gives actionable guidance for using the tool correctly. However, it does not explicitly contrast with alternatives (e.g., when to choose copy over move or trash), which would further clarify usage.

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