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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds nothing beyond that. It omits the practically important behaviors — that invite emails are sent by default (send_updates defaults to 'all'), what happens with duplicate events, and whether the created event's ID is returned. The second sentence largely re-lists schema fields rather than disclosing 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?

Two short sentences with the action front-loaded, so an agent can scan it instantly. The second sentence is mostly redundant with the input schema, which costs it a point on economy but doesn't hurt readability.

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 10-parameter mutation tool with no output schema, the description should at minimum say what comes back (event ID for follow-up calls) and note the invitation side effect. As written it covers only the field surface, leaving the agent without the return contract or the notification consequences of the default send_updates value.

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 description coverage is 100%, so every parameter including defaults for calendar_id, add_meet, and send_updates is already documented in the schema. The description's list of settable fields ('title, time, attendees, description, location, Google Meet links') restates those properties without adding format, constraints, or edge-case meaning, so the schema baseline of 3 applies.

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 a specific verb+resource ('Create a new calendar event') that unambiguously separates it from calendar_update_event, calendar_get_event, and calendar_list_events. It doesn't explicitly name the sibling it differs from, but the create-vs-modify distinction is clear from the name and first sentence.

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?

There is no explicit when-to-use guidance, no prerequisites (e.g. calendar write scope, which account is used), and no mention of the natural alternative calendar_update_event for modifying an existing event. The agent must infer that 'create' means new events only, which is reasonable but never stated.

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