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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower; the description still adds genuine value by disclosing that large details are truncated and that provider events are immutable. The displayTime.label vs startAt/endAt guidance is real response-interpretation context beyond what annotations carry.

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 sentences, no filler, and the selection condition is front-loaded. Slight inefficiency in that the opening clause states usage rather than purpose, pushing the actual tool behavior to the reader's inference.

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 an output schema present, the description needn't enumerate return fields, and it does cover the tricky interpretation cases (truncation, timezone/instant distinction, provider read-only). The remaining gap is sibling disambiguation against find_events and get_schedule, which a 2-param getter would benefit from.

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 100% and both eventRef and occurrenceRef are documented in the schema with patterns, so the baseline is 3. The description adds nothing about the two parameters — notably it never mentions occurrenceRef or that eventRef is required, so it does not supplement the schema.

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 frames the tool by need ('when you need one event occurrence') rather than stating a verb and resource, so the actual operation (fetch a single event by reference) is only implied. It does distinguish singular occurrence retrieval from the list-oriented siblings like find_events or get_schedule, but only implicitly and without naming them.

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?

'Use this when you need one event occurrence' gives a positive selection condition, and the displayTime note steers interpretation for timed events. However, no alternatives are named (find_events, get_schedule) and there are no explicit exclusions, leaving the agent to infer when not to use it.

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