Create Mailbox

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

With no annotations, the description carries the full behavioral burden. It does disclose meaningful behavior: intermediate path segments are created if needed, and the two nesting approaches are mutually alternative. It says nothing about permission requirements, behavior when the mailbox already exists, or failure modes, leaving real gaps for a mutation tool.

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?

Two short paragraphs, front-loaded with the core action before the nesting detail, and every sentence earns its place. Minor overlap with the schema, which already notes that name may contain '/', keeps it off a 5.

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?

An output schema exists, so return values need not be described, and all three parameters are covered by the schema. For a mutation tool with zero annotations, however, the absence of any statement about preconditions, duplicate mailboxes, or error behavior leaves the definition only adequate rather than 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 description coverage is already 100%, so a 3 is the floor. The description adds value the schema does not: it spells out the interaction between parent_mailbox and the slash-in-name form (e.g., parent_mailbox="Projects" + name="2024" yields Projects/2024, and parent_mailbox may be omitted when a full path is given).

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 states a specific verb and resource ('Create a new mailbox (folder) in the specified account'), which is unambiguous and readily separable from the read-oriented siblings like list_mailboxes and get_mailbox_unread_counts. It does not, however, explicitly name or contrast itself with any sibling, so it stops short of a 5.

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 conditional guidance for the two creation idioms ('use parent_mailbox + name' vs. 'pass a full slash-separated path as name and omit parent_mailbox'), which is genuinely useful. But it never says when to create a mailbox versus using an existing one or what preconditions apply, so usage is implied rather than fully framed.

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