Create a calendar event

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

Annotations indicate a state-changing operation (readOnlyHint false). The description goes beyond the annotations by disclosing that adding attendees places the event on their calendars, and that emails are only sent when send_updates is set. It also explains an important API quirk (exclusive end date for all-day events). This adds behavioral context that the annotations alone do not provide.

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?

The description is three sentences with zero fluff. It front-loads the primary action ('Create an event') and then packs the critical nuances (date formats, exclusive end, attendee/email behavior) into compact, useful clauses. Each sentence earns its place; no redundant or vague phrasing.

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 an 11-parameter tool with no output schema, the description covers the key gotchas: timed vs. all-day handling, date-exclusivity, attendee calendar placement, and send_updates default. It does not mention the return value, but that is acceptable given no output schema. It omits no critical information that an agent needs to call it correctly.

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 each parameter already has a description. The description adds value by clarifying the difference between timed ISO 8601 offsets and plain dates for all-day events, and by explaining the exclusive end-date behavior. It also notes the side effect of attendee emailing tied to send_updates. This goes beyond the schema's literal param descriptions, so a 4 is appropriate.

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 opens with the specific action 'Create an event,' which is a clear verb + resource. It further distinguishes the tool's purpose by detailing the two valid input formats (timed vs. all-day), which are unique to creating an event. This makes it unambiguous against sibling tools like calendar_update_event or calendar_delete_event.

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 gives clear usage context: when to use timed vs. all-day formats, how to set attendees, and the effect of send_updates. It does not explicitly name alternatives (e.g., use calendar_update_event to modify) but the create/update distinction is implied by the verb. It provides situational guidance without excluding alternatives, which earns a 4 rather than a 5.

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