list_mailboxes

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

With no annotations, the description carries the disclosure burden. 'List' conveys a read-only action and the description clarifies the two account scopes, but it does not mention authentication requirements, how empty or invalid accountName are handled, or the exact set of mailbox properties returned. It is adequate for a simple read-only utility but leaves some behavior unspecified.

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 a single, front-loaded sentence with no unnecessary words. It presents the main verb and resource first, then the alternative scopes. Every part adds meaningful information.

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 one-parameter, no-nested, no-output-schema tool, the description is complete. It tells the agent what the tool does and exactly how the one optional parameter affects behavior.",

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%: accountName is already described as the account to list mailboxes for, or omitted for all accounts. The tool description mostly restates this same guidance, so it adds little beyond the schema. Baseline 3 applies because the schema already documents the only parameter.

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 clearly states that the tool lists mailboxes and defines its two valid scopes: a single Mail.app account or all accounts. The verb-resource pairing is unambiguous and distinguishes it from sibling tools like list_accounts (accounts vs mailboxes) and get_mailbox_info (single mailbox details).

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 implies when to use the tool by defining the scope, and it explicitly says to omit accountName for all accounts. However, it gives no direct guidance about when to prefer this tool over alternatives such as list_accounts or get_mailbox_info, so usage context is mostly self-evident rather than spelled out.

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