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

Annotations only say readOnlyHint=false, so the description carries the burden. It discloses that the event lands on the real calendar immediately, that attendees are deliberately unsupported to avoid Google emailing invites, and that a reconnect result should be handled by linking to /user/integrations/gmail. This is material behavior beyond data types and schema.

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?

Six short sentences, each carrying distinct information: purpose, usage gate, timestamp format, calendar selection, attendee limitation, and re-auth handling. There is no filler, though the required-fields reminder slightly duplicates the schema.

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 mutating tool with no output schema, it covers creation semantics, formatting, calendar routing, side-effect constraints, and failure remedy. The only notable omission is describing what a successful response contains (e.g., event id/status), but this is not critical for invoking the tool 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?

The schema already describes all 7 parameters, so the baseline is 3. The description adds an RFC3339 example with timezone, reiterates which fields are required, and explains how to source calendar_id from list_google_calendars and what 'omit' means. This goes beyond schema but does not cover every parameter (e.g., account) in prose.

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 ('Create') and resource ('new event on the user's Google Calendar'), and clarifies scope ('one new event') so it is distinct from update_calendar_event or get_calendar_events. It also highlights required vs optional fields upfront.

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?

Explicitly gates use on user request ('Use only when the user asked for the event'), because creation has immediate real-world effect. It also gives routing for secondary decisions (calendar_id from list_google_calendars), though it does not explicitly name update_calendar_event as the alternative for modifying an existing event.

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