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

Annotations already declare destructiveHint=true and openWorldHint=true, so the safety profile is partly covered. The description adds genuinely non-obvious behavior: cancellation emails are sent to every guest, and the deletion is 'immediately and irreversibly.' That external side effect cannot be inferred from the annotations. It doesn't cover error cases or recurring-series semantics.

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 tight sentences with no filler; the destructive consequence and the confirmation requirement are front-loaded and easy to scan.

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 no output schema, the description does the necessary work of flagging irreversibility, guest notifications, and the confirm-first requirement. An agent can call it correctly, though the undocumented eventId parameter and lack of guidance on recurring events leave a small gap.

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 only 50% — eventId has no description at all, while mailbox documents itself and points to list_authorized_mailboxes. The description supplies no parameter guidance (no format, no how-to-obtain an eventId), so it fails to compensate for the coverage gap.

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+resource ('Delete one event or occurrence') with useful scope detail — the 'or occurrence' phrasing signals single-occurrence deletion. It doesn't explicitly differentiate itself from delete_google_calendar_event or delete_outlook_calendar, but the Outlook naming and event-level target make the intent 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 a concrete usage precondition: 'Ask the user to confirm before calling this.' That is real routing/behavioral guidance for a destructive action. It stops short of naming alternatives (e.g., delete_outlook_calendar for the whole calendar, or cancel_invitation) or stating when not to use it.

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