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

Goes well beyond the annotations: discloses the side effect that Google sends invite emails automatically when attendeeEmails is provided (sendUpdates=all), states the account prerequisite, explains the default account selection behavior, and documents the return shape { eventId, htmlLink }. Annotations only carry the read/write/destructive/idempotent bits; this description delivers the operational behavior an agent needs to predict consequences.

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 dense sentences that front-load the core purpose, then cover side effects, prerequisites, default behavior, and return value in logical order. Each sentence earns its place; the only minor redundancy is that the sendUpdates=all detail also appears in the attendeeEmails schema description.

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 8-parameter tool with no output schema, the description covers prerequisites, side effects, default parameter behavior, and the return format. Remaining gaps are minor (no explicit error behavior when no Google account is linked, and no explicit routing to sibling calendar tools), but annotations and full schema coverage already carry much of the burden.

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 every parameter already has a description, so the baseline is 3. The description mostly echoes the schema's account-selection and invite-email notes rather than adding substantially new parameter meaning; the only marginal addition is naming the sendUpdates=all mechanism explicitly.

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 the specific verb 'Create' plus an explicit resource ('Google Calendar event') and the optional attendee invitation behavior. The create-vs-update-vs-delete vs-check availability distinction among sibling calendar tools is immediately clear without opening any other tool definition.

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?

Provides clear context for when it applies: requires a connected Google account linked to the workspace, and defaults to the first such account when googleAccountId is omitted. However, it does not explicitly name sibling alternatives (e.g., check_calendar_availability for availability checks, update_calendar_event for modifications), leaving when-not-to-use guidance implicit.

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