create_mailbox

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

Adds substantial behavior beyond the annotations: an existing mailbox reports already_exists without changes, parent levels are only created if the server does so itself, and unknown statuses are not auto-retried. It also surfaces the organize permission requirement, which no structured field declares.

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?

Four sentences, each contributing a distinct fact (creation semantics, permission, idempotency, parent/retry behavior), front-loaded with the core action. Slightly dense, but nothing is redundant with the schema or annotations.

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?

With an output schema covering the already_exists result and 100% schema coverage on both parameters, the description only had to supply behavioral and permission context, which it does fully, including the recovery path via list_mailboxes.

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 already 100% and the schema itself documents the wildcard and trailing-delimiter restrictions. The description still adds value by supplying concrete delimiter examples and stressing 'exact server name', clarifying the format expected for the mailbox 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?

States a specific verb and resource ('Create one mailbox/folder') and pins the scope to an exact server name, which distinguishes it from siblings like list_mailboxes and save_to_mailbox. The parenthetical delimiter examples make the target object unambiguous.

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?

Gives clear operational context: requires the organize permission, and on an unknown status the agent must verify with list_mailboxes rather than retry. It does not explicitly contrast against the closest sibling, save_to_mailbox, leaving some ambiguity about when to create a mailbox versus targeting one.

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