List Calendars

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description usefully adds the required permission and the cursor-based pagination contract, but leaves openWorldHint and the actual return shape unexplained despite a list of calendars potentially spanning accounts.

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?

Three short sentences, each earning its place: what it does, what auth it needs, how to page. It is front-loaded and free of filler, though it is terse enough that it borders on under-specified.

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 an output schema present, return values need no explanation, and all three parameters are documented in the schema. The description covers permissions and paging, which is nearly everything an agent needs for a simple read-only list operation; only the relationship to sibling calendar tools is missing.

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 100%, so limit, cursor, and mailbox_id are already fully documented, including the omit-when-single-mailbox rule. The description reinforces the paging semantics of limit and cursor but adds no new parameter detail beyond that.

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 opens with a specific verb and resource ('List calendars in the selected mailbox'), which distinguishes it from mailbox_list_calendar_events and mailbox_get_calendar. It stops short of naming the closest sibling, so the agent must infer that this enumerates calendar containers rather than calendar 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?

It gives two concrete operating instructions: the required scope (calendar.read) and the paging pattern (small limit, continue with returned cursor). It does not say when to prefer mailbox_get_calendar or when listing is unnecessary, so usage is implied rather than contrasted.

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