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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, non-open-world), so the description's added value is real: the default paging behavior without a window, the semantic shift to calendarView when a window is given, and the auth note 'No new scope'. It stops short of describing ordering, timezone, or result-shape behavior.

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 short sentences, front-loaded with the core purpose followed immediately by the two behavioral modes. Every sentence carries information the schema and annotations do not, with no filler.

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 three-parameter read tool with no output schema and full annotation coverage, the description supplies the essential missing pieces: default behavior, windowed behavior, and scope implications. Remaining gaps (pagination limits, ordering, timezone of returned events) are minor for this tool class.

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 33% (only startUtc documented), so the description must compensate and it does so partially: it explains that `top` bounds the count in the no-window mode and that startUtc/endUtc pair to form a window. It gives no default value, maximum, or accepted format for `top`, so half the gap remains.

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 and resource (list calendar events) scoped to the authorized user, which is measurable against siblings like list_outlook_messages or find_meeting_times. It does not explicitly name or contrast a sibling, so it stays at 4 rather than 5.

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?

It clearly distinguishes two usage modes: omitting a date window returns the next `top` events, while supplying startUtc + endUtc switches to calendarView with recurring-instance expansion. That is concrete mode-selection guidance, though it never names an alternative tool or an exclusion condition.

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