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 real behavioral context beyond that: the default sort is newest-first, the result set is account-scoped, and the shape of what each calendar record contains. It does not discuss pagination behavior beyond what the schema says.

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 tight sentence that front-loads the scope and default ordering, then lists returned fields, followed by the endpoint. No filler or restatement of the tool name.

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 no output schema, the description usefully compensates by enumerating the returned fields and the default ordering, which is the key information for a read-only listing tool. Filtering and pagination semantics live in the schema; the only minor gap is any mention of total counts or how to page through large accounts.

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%, so page, page_size, sort_by, sort_order and calendar_ids are all documented in the schema itself. The description only echoes the default ordering (which maps to sort_by=created), adding marginal meaning. Baseline 3 is correct.

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 (List) and resource (the account's calendars), enumerates the returned fields (id, title, timezone, default flag, landing-page links, event/subscriber counts), and names the endpoint GET /calendars. An agent can distinguish it from the singular addevent_get_calendar and from addevent_list_calendar_subscribers 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?

Usage is implied by the list-shaped purpose and by the default ordering note, but there is no explicit when-to-use guidance, no statement of when to prefer addevent_get_calendar or the subscriber listing instead, and no prerequisites or scope limits mentioned. Minimum viable.

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