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

Annotations already declare write, open-world, idempotent, non-destructive. The description adds the genuinely useful side effects: Google sends real invitations when attendees is non-empty, no attendees are invented, and retries require an idempotency_key. It omits prerequisites such as needing a connected/authorized calendar (cf. the get_calendar_connection sibling), which is the remaining behavioral gap.

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?

Four short sentences, front-loaded with what is created and immediately followed by the scope exclusion, then parameters, then the invitation side effect. No sentence is filler and nothing important is buried.

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 9-parameter open-world write tool with no output schema, the description covers the mutation's blast radius and retry story well. It never states what comes back (event identifier/link) or which connection/permission is required, which leaves a small but real gap for an agent planning a follow-up call.

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%, so the baseline is 3; the description still adds intent beyond the schema by telling the agent to pass the exact title, timezone-bearing start/end, and intended attendee emails, and by flagging idempotency_key as a hard requirement for safe retries. It does not explain the google_meet or user_goal parameters, but the schema already does.

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 and resource ("Create one owner-authored Google Calendar event on the site's owned write calendar") and immediately scopes it against the obvious confusion: it is not a booking and does not consume appointment capacity. An agent can distinguish this from manage_appointments, book_callback_slot, or get_calendar without opening any schema.

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?

Explicit exclusion is given ("does not create a booking or bypass appointment capacity") plus the precondition that attendees must be non-empty for invitations to go out. It stops short of naming the sibling to use when a real booking is wanted, so routing is implied rather than directed.

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