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

Annotations already declare readOnlyHint=false and destructiveHint=false; the description reinforces and extends this by stating the action is reversible via restore_message and that the target folder is located by name rather than a fixed path. It also discloses the return value. It does not add permission/auth details, but the annotation coverage makes the bar lower.

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?

Three short sentences, each doing distinct work: what it does, that it's reversible plus the alternative, and what it returns. Front-loaded with the action and destination, zero 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?

For a 3-parameter, single-message mutation with no output schema, the description covers the destination semantics, the reversibility, the routing alternative, and the return value. Nothing an agent needs to invoke it correctly is missing.

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 100% (uid, folder, mailbox all documented inline), so the schema carries parameter meaning. The description only implies that uid identifies a single message and adds no format, default, or validation detail beyond the schema. Baseline 3 applies.

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 (move), a single message as the resource, and the exact destination (Junk/Spam folder). It explicitly names the sibling tools it is not (move_message for other folders, restore_message for undo), so an agent can distinguish it without opening any schema.

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?

Gives explicit when-to-use (any message into Junk/Spam regardless of folder naming) and a named alternative for the adjacent case ('For any other destination folder, move_message is the general move'). It also notes the undo path, covering the reverse operation.

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