create_mailbox

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

Annotations already indicate this is an idempotent write operation. The description adds meaningful behavioral context by explaining the nested folder separator convention and suggesting checking existing folders via list_mailboxes, which goes beyond the structured 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?

Two sentences, front-loaded with the core purpose, and every word earns its place. The advice about separators and list_mailboxes is valuable without unnecessary detail.

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 2-parameter create tool with idempotentHint and no output schema, the description covers purpose, syntax, and a pre-check step. It doesn't explain potential errors or permission requirements, but those are less critical given the annotations and simplicity.

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?

The schema covers 100% of parameters with descriptions. The description adds a minor but useful clarification about the path separator, but it mostly reinforces what is already in the schema.

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 the verb 'Create' and resource 'mailbox (folder)', distinguishing it from sibling tools like rename_mailbox, delete_mailbox, and list_mailboxes. It also adds a key detail about nested folder syntax, making the purpose 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?

The description provides explicit guidance on using '/' as a separator and recommends using list_mailboxes to see existing folders. While it doesn't explicitly exclude any scenarios or mention alternatives, the context is clear enough for a create operation.

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