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

With no annotations present, the description carries the full burden and does a strong job: it discloses cascade destruction ('every event on it'), irreversibility ('WARNING: this is not recoverable'), and the required confirmation step. It does not address permission/ownership requirements or behavior on a non-existent/primary calendar, leaving minor gaps.

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?

Three front-loaded sentences: action and scope first, then restriction, then warning and confirmation instruction. No repetition or filler; each sentence carries distinct weight, which is appropriate for a destructive tool.

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 2-param tool with no output schema, the description covers core semantics, the primary-calendar constraint, and the irreversible nature of the action. The main gap is that the calendarId parameter is left undocumented in both the schema and the description, with no pointer to list_google_calendars as the source of valid IDs.

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 only 50%: mailbox is well-described, but calendarId has no schema description and the tool description adds nothing about its format, provenance, or how to obtain it (e.g., via list_google_calendars). The agent must infer calendarId's meaning from the tool name and sibling list, which is a material gap for a required 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?

The description states a precise verb plus resource ('Delete a secondary calendar and every event on it') and adds clear scope by excluding the primary calendar. It is clearly about calendar deletion rather than event deletion, though it does not name the nearest sibling delete_google_calendar_event to differentiate explicitly.

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 gives clear context: it applies only to secondary calendars ('The primary calendar cannot be deleted') and mandates user confirmation before invocation ('Ask the user to confirm before calling this'). It does not name any alternative tool (e.g., delete_google_calendar_event) or spell out when a delete should be avoided in favor of another action, so it stops short of the top tier.

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