List mailboxes

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

Annotations already declare readOnly, idempotent, and non-destructive. The description adds context about when to use it but does not disclose additional behavioral details such as what the response contains (e.g., mailbox names and IDs) or any performance characteristics. Thus it adds only modest value beyond 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?

The description is one concise sentence that directly states the purpose and usage conditions without unnecessary words. It is well-structured and front-loaded with the key trigger conditions.

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?

Given the simplicity of the tool (one parameter, no output schema), the description is mostly sufficient. It indicates the intended use and context, though it omits explicit mention of the return value (a list of mailboxes). However, this is largely obvious from the title, so the description is nearly complete.

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 for the single parameter accountId is 0% and the description does not mention it. Since schema coverage is low, the description should compensate by explaining the parameter, but it fails to do so. The parameter name is self-explanatory, but the description provides no explicit 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 title 'List mailboxes' provides a clear verb and resource, and the description specifies when to use it (needing a folder other than Inbox or an opaque destination mailbox ID for move/copy operations). This distinguishes it from sibling tools like mail_move and mail_copy.

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 explicitly states the conditions for use: when a task needs a folder other than Inbox or needs an opaque destination mailbox ID for move and copy operations. This gives clear guidance on when to invoke the tool.

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