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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds useful behavioral context beyond that: it explains that the list includes sync state, excludes automatically linked MMK/Nausys calendars, and that an empty list means no external calendar is connected.

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 tight sentences with zero waste. The core purpose is front-loaded, followed by the two most important interpretation details: excluded automatic calendars and the meaning of an empty list.

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 with a fully documented single parameter and annotations covering safety, the description is nearly complete: it says what is returned, what is excluded, and what an empty result means. The only minor gap is that it does not detail the exact return fields (e.g., calendar id, type, sync state values) in the absence of an output schema.

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%: the single boat_id parameter is fully documented as 'Boat id, from list_boats.' The description reinforces the one-boat scope but adds no syntax, format, or sourcing detail beyond the schema, so the baseline of 3 applies.

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 names the specific verb (lists), resource (external calendars), and scope (connected to one boat), and explicitly distinguishes the content by excluding MMK/Nausys auto-linked calendars. An agent can tell this apart from add_calendar, remove_calendar, and sync_calendar 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: use this to see which external calendars are connected to a boat, with the caveat that MMK/Nausys are not included. However, no explicit when-to-use guidance is given relative to sibling tools like add_calendar or sync_calendar, and no prerequisites or alternatives are named.

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