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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful behavioral context about supporting Google/Microsoft accounts and the requirement to use the returned calendar.id rather than a display name, which goes beyond annotations.

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 sentences with no filler. The core action is front-loaded, and the critical usage constraint (use calendar.id, not display name) follows immediately. Every sentence earns its place.

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 simple read-only list tool, the description covers the essential workflow: list calendars, use the returned id, and pass account context when needed. It does not describe pagination or response shape, but those are partially inferable from the parameter names, and annotations carry the safety-related context.

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 only 25%: account_id is richly documented, but limit, cursor, and offset have no descriptions. The main description reinforces the connection between the tool and account_id but does not explain pagination parameter behavior, leaving those parameter semantics to be inferred from their names.

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 clear action and resource: 'List calendars for the connected Google or Microsoft account.' It also explains the purpose of the result ('Use the returned calendar.id before listing, creating or updating events'), which differentiates it from sibling calendar tools like calendar_get_calendar or calendar_list_events.

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 practical routing guidance: obtain a calendar.id from this tool before listing, creating, or updating events, and never pass a display name as calendar_id. It does not name sibling alternatives explicitly, but the 'use before...' pattern clearly positions this tool as the entry point for calendar operations.

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