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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context by disclosing the required Calendars.ReadWrite scope (an auth/permission requirement), but it omits result limits, attendee-count caps, and what the returned candidate list looks like.

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 the action front-loaded and no filler. The endpoint name is mildly redundant with the title but still informative for the calling agent.

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 5-parameter, no-output-schema tool, the description leaves the window/duration/candidate semantics entirely undocumented and says nothing about the shape of the returned time candidates. Annotations cover safety, but the functional contract is too thin.

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 0% across 5 parameters, and the description supplies no parameter meaning at all. An agent cannot learn from either source what startWindowUtc/endWindowUtc formats are expected, what meetingDurationMinutes defaults to, or how maxCandidates behaves.

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 specific verb and resource ('Find free meeting times across attendees') and names the underlying Graph endpoint, so an agent knows exactly what the tool does. It is distinguishable from siblings like compose_meeting_invite or list_calendar_events, though it does not explicitly name an alternative to route against.

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?

There is no statement of when to use this tool versus alternatives such as list_calendar_events, compose_meeting_invite, or get_working_calendar. The only contextual hint is the scope reuse note, which is not usage guidance.

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