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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the agent knows this mutates state without destroying data. The description adds nothing beyond that: no reversibility note (can it be undone? does restore_message apply?), no permission/mailbox-auth requirements, no note on what happens to the source copy.

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?

A single tight sentence with the action front-loaded and the helper-tool hint appended. Nothing wasted.

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 non-destructive mutation with no output schema and full schema coverage, the description is minimally sufficient. It omits reversibility and any post-move state expectations, which an agent would benefit from knowing.

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 100%, so the baseline is 3, but the description goes further by telling the agent how to obtain a valid destination value. It does not clarify the optional 'folder' source parameter that defaults to INBOX, which is a minor gap.

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?

States a specific verb and resource ('move a message') plus the target ('to another folder'), which is unambiguous. It does not distinguish itself from near-siblings like label_message or restore_message, but the action itself is unmistakable.

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 parenthetical '(use list_folders for valid destinations)' usefully routes the agent to a helper tool for resolving the destination value. However, it gives no guidance on when to move vs. label, copy, delete, or restore, which is the harder selection decision among siblings.

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