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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds a useful hint about the shape of the result (time, attendees, status), but says nothing about behavior when the event or connection is missing, or whether cross-calendar lookups fail silently. That is an acceptable but not rich disclosure given annotation coverage.

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?

One tight sentence with the core action and result front-loaded and no filler. It is arguably too thin rather than too long, but on pure structure and economy it holds up.

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 three-parameter getter with full schema coverage and complete annotations, the description covers the essential what. What it omits is ambiguously important: the distinction from get_calendar_event, and the failure mode when an event id does not resolve within the given connection.

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 100%, so eventId, calendarId and connectionId are all documented, including the primary-calendar default. The description adds no further semantics beyond what the schema states, so the baseline of 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 ('Fetch one event') plus the resource ('event from a connected calendar') and even previews the payload ('time, attendees and status'). It implicitly contrasts with list_connection_events by saying 'one', but never explicitly differentiates from the similarly named get_calendar_event, which an agent could easily confuse with this tool.

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 contains no when-to-use, when-not-to-use, or prerequisite guidance. It does not tell the agent to call list_connection_events first, nor does it explain when to prefer this over get_calendar_event — that discovery work is pushed entirely onto the schema (which does mention 'Event id from list_connection_events').

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