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

Annotations already mark the operation as destructive and not read-only. The description adds valuable behavioral details beyond annotations: flags and original dates are preserved, and the operation requires all UIDs to come from the same source folder. No contradiction with annotations.

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 sentences carry the essential information: the action, the preservation guarantees, the batching/destination constraints. No wasted words, and the key usage instruction is placed where it is most likely to be read.

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 three-parameter tool with no output schema and annotations covering destructive/read-only behavior, the description is sufficient. An agent knows what to call, how to batch UIDs, what constraints apply, and what behavior to expect regarding flags and dates.

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% and the schema already documents uids, to, and from, including batching guidance and the INBOX default. The description still adds value by making explicit the same-source/same-destination invariant, which the schema does not directly state.

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 opens with a specific verb and resource: 'Move messages from one IMAP folder to another.' The additional constraints about same source folder and same destination further clarify exactly what the tool does, distinguishing it from archive/delete/folder operations.

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?

It gives clear usage context: 'Filing a backlog is what this tool is for' and instructs to pass every UID in one call and make one call per destination for multiple folders. It does not explicitly contrast with alternatives like archive_email or delete_email, but the usage guidance is strong and concrete.

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