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

With no annotations, the description carries the full burden and does well: it discloses the side effect of emailing invitees, the agent-context restriction that blocks it, the 20-attendee cap, the 30-minute default, and the Meet-link side effect. It stops short of stating calendar-permission requirements or what happens on conflict/invalid timezone.

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?

Dense and front-loaded — the core action leads, then format rules, then the constraint, then the return. Semicolon-chained clauses make it slightly run-on, but nearly every clause carries non-redundant information.

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 6-parameter mutation with no annotations and no output schema, the description covers the action, key parameter formats, a hard restriction, and the return value. Missing only edge-case behavior (missing primary calendar, invalid timezone, attendee failure) which keeps it from being complete.

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 only 33%, yet the description compensates: it gives the ISO date-time format with a concrete example for start, explains the end-vs-minutes tradeoff with the default, and documents attendees as emails capped at 20. Only title is left unstated, which is self-evident.

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 with scope: 'Create an event on the user's primary Google calendar.' An agent can distinguish this from list_events/update_event/delete_event, though no sibling is named explicitly to route away from create_booking_link or find_free_time.

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 one concrete exclusion ('from an agent's own turn inside Caddie that's refused' for attendees) and a defaulting rule ('give end or minutes (default 30)'), but gives no guidance on when to prefer create_booking_link or find_free_time, or what to do when the agent needs to invite guests.

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