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

Annotations already declare readOnly=false, openWorld=true, idempotent=false and destructive=false, so safety is covered. The description adds nothing behavioral beyond that: it does not say side effects propagate to an external provider calendar, whether attendees receive invitations, whether duplicates are created on retry (idempotent=false makes this relevant), or what is returned.

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?

One front-loaded sentence with a tightly scoped parenthetical; nothing is redundant. It is arguably under-specified rather than over-long, which is penalized elsewhere, not here.

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?

A 7-parameter mutation tool with four required fields, openWorld=true, and no output schema. The description should at minimum explain the external side effects, attendee invitation behavior and how the required connectionId is obtained; it covers none of that.

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 57%: title, description and attendees have no schema descriptions at all, and the description adds no parameter guidance. It does not explain attendee semantics (do they get invited?), the calendarId default, or the connectionId lookup even though the schema hints at it.

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 an event on a connected calendar') and rules out the biggest conceptual confusion with create_booking. However, it never distinguishes itself from the very similarly named sibling create_calendar_event, which an agent would hit first when scanning sibling names.

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 explicit exclusion and redirect ('not a Caly booking; use create_booking for those'), which is genuine when-not guidance. But the most confusable sibling is create_calendar_event, and the description says nothing about which one applies when, nor any prerequisite such as needing a connectionId from list_calendar_connections.

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