delete_mailbox

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

Goes well beyond the destructiveHint=true annotation: it discloses that no Mail confirmation appears, that the first use per account triggers a macOS password prompt stored in the keychain (never visible to the agent), and that deletion is server-side and limited to server-confirmed-empty mailboxes. It stops short of stating whether the deletion itself is reversible, which matters for a destructive tool, so not a full 5.

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?

Front-loaded with the action and constrained to one dense paragraph where every clause carries operational information. The keychain aside and the "Mail lets no app do this" framing are slightly conversational but still earn their place by explaining the auth prompt.

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 present and annotations covering the destructive profile, the description still supplies everything an agent needs: emptiness precondition, auth flow, sibling tool to use first, and scope exclusions. Nothing material is missing for a 2-parameter destructive tool.

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 100%, so the schema already explains both parameters, including that account disambiguates names across accounts and that mailbox accepts a name or path. The description only reinforces the mailbox concept as a folder or Gmail label, adding little beyond structured fields. Baseline 3 applies.

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 ("Delete an empty mailbox (a folder, or a Gmail label) on its mail server") and immediately distinguishes itself from siblings by noting Mail's own API cannot do this, so it is a server-side operation rather than a Mail-app action like move_mail.

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 the explicit precondition (only a mailbox the server says is empty), the alternative to use first ("move its messages out first with move_mail, which can be undone"), and a hard exclusion list (inbox, sent mail, drafts, trash, junk, provider folders). An agent knows both when to call it and when not to.

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