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

Annotations already establish this is a safe read operation (readOnlyHint=true, destructiveHint=false), so the safety profile is covered. The description usefully discloses that the response includes the guest list with addresses and acceptance status, which is real added context given no output schema, but it says nothing about auth scope, permissions, or rate limits.

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?

A single front-loaded sentence with no filler; the key differentiator (single, full event) comes first and the extra return detail follows. Efficient, though it leans slightly toward describing output rather than splitting purpose and usage.

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 partly carries the return-shape burden by mentioning the guest list and RSVP status. However, two of three parameters are unexplained and there is no routing guidance, leaving meaningful gaps for a tool that must be called with a specific eventId and calendarId.

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 33% — just 'mailbox' is documented (with a pointer to list_authorized_mailboxes). 'eventId' and 'calendarId' are undocumented in both schema and description, and since the coverage is low the description needed to compensate but does not mention either parameter at all.

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?

"Read one event in full" gives a specific verb (read) and resource (a single calendar event), and the detail about the guest list sharpens what "in full" means. It implicitly distinguishes itself from list/search siblings by emphasizing a single event, though it never names them 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?

Usage is only implied by "one event" versus the existence of list_google_calendar_events and search_google_calendar_events. There is no explicit when-to-use guidance, no statement of prerequisites (e.g. needing an eventId from a list/search call), and no named alternative.

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