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

Annotations already state destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered; the description then adds the non-obvious async semantics (queued, not provider-completed), the required polling follow-up, and retry discipline with the idempotency key. This is meaningful behavior an agent could not infer from the structured fields. Minor wording issue: 'an uncertain send' reads like residual copy from send_email, which slightly muddies the retry rule for a move 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?

Four short sentences, front-loaded with the core action, with a small amount of waste in the 'uncertain send' phrasing that does not fit a move tool. Nothing is repeated from the annotations or schema.

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?

With no output schema, the description correctly takes on the return-value burden by stating that a queued operation is returned and that get_mail_action is the polling target. It stops short of describing what the queued operation contains or how to detect terminal failure, but an agent has enough to call and follow up 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 only 25% – only operationId is documented in the schema. The description reinforces operationId's purpose (returned to the caller, reused only for that exact retry), but adds nothing about accountId, messageId or destinationFolderId. It therefore only partially compensates for the low coverage, landing at the baseline.

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 first sentence gives a specific verb and resource ('Move a message to another folder'), which is clear and action-oriented. It does not, however, contrast the tool with its closest sibling (archive_email) or explain what distinguishes a move from an archive, so sibling discrimination is left to inference.

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 gives concrete procedural guidance: returns a queued operation, poll get_mail_action with the returned operationId, and never retry with a new operationId. That is strong when/how guidance, though it names no alternative tool or condition under which a caller should choose archive_email or a different path instead.

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