create_mailbox

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. Beyond stating that it creates a mailbox and supports nesting, it does not mention required permissions, behavior on duplicate mailbox names, whether changes are immediately visible, or what happens on failure. For a mutation operation, this is a significant gap.

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 sentence that earns its place: it names the verb, the object, the application context, and the nesting capability. There is no filler or repeated 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 simple create operation with only three parameters, full schema coverage, and no output schema, the description is sufficiently grounding. It defines the operation and the nesting choice, and the schema fills in the required fields. Additional context about errors or side effects would be nice but is not critical for correct invocation.

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%, with each parameter already explained meaningfully in the input schema. The mention of top-level vs nested mailboxes in the description aligns with parentMailboxName but adds little beyond what the schema already communicates, so the baseline 3 is appropriate.

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?

Description uses the specific verb 'Create' and resource 'new mailbox (folder) in a Mail.app account', making the action and target unmistakable. The additional 'Can create top-level or nested mailboxes' captures the key variation and clearly differentiates it from sibling tools like list_mailboxes and get_mailbox_info.

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 gives useful context about what the tool can do, including top-level vs. nested creation, which maps directly to the optional parentMailboxName. It does not explicitly compare to alternatives, but none of the sibling tools perform mailbox creation, so clear exclusion language is not necessary.

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