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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context: the slots are real bookable availability from active connected calendars, and the returned calendar IDs, ISO starts, timezones, and provider resource IDs must be copied exactly into a booking proposal.

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?

The description is three tightly written sentences. It front-loads the core purpose, then adds exclusions and downstream output handling without any wasted phrasing.

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?

With annotations covering the safety profile and the schema fully documenting both parameters, the main remaining burden is return-value guidance because there is no output schema. The description partially handles this by naming the key returned fields to copy into a booking proposal, though it does not describe the full response shape or edge cases such as no availability.

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%, and the parameter descriptions already explain calendarShortId as an exact 4-character ID and date as a calendar-local YYYY-MM-DD value. The tool description adds little parameter-specific detail beyond referencing active connected calendars, so the schema carries the semantic load.

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 states a specific verb+resource: finding real bookable appointment slots in the user's active connected calendars. It also explicitly distinguishes this from existing-event lookup and calendar configuration, so an agent can tell it apart from siblings like findAppointments or calendar_update_settings.

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?

The description gives clear usage context: use it for real bookable availability, not for existing-event lookup and not for calendar configuration. It does not name the alternative tools directly, but the exclusions provide enough routing guidance for an agent.

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