list_calendar_details

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

With no annotations, the description carries the full behavioral burden, and it does disclose real behavior: what each calendar entry carries and the non-obvious fact that over CalDAV iCloud may not expose subscriptions at all. It stops short of declaring this is a read-only operation or describing ordering/size of the result set, which for a no-annotation tool is a moderate gap.

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, front-loaded with the fields returned, followed by a targeted edge-case caveat. Every clause earns its place, though the field enumeration is slightly dense in list form.

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 zero-parameter read tool with an output schema, the description is complete enough: it explains what the entries contain (the output schema only names fields, it does not explain semantics like 'legacy reminders list') and adds the subscription-exposure caveat. It lacks any when-to-use routing against list_calendars, keeping it short of a 5.

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?

The tool takes zero parameters, so there is nothing to document and the baseline of 4 applies. The description correctly adds no parameter noise.

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 resource (calendars) and enumerates the detail fields returned (colour, contents type, write permission, subscription status), which distinguishes it from a thin 'list_calendars' by the richness of its payload. However, it never explicitly names or contrasts with the sibling list_calendars, so the differentiation is implied rather than stated.

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?

There is no statement of when to use this tool versus list_calendars or the reminder-list siblings. The only contextual note is a CalDAV/iCloud caveat about subscriptions, which is behavioral rather than usage routing. An agent must infer the use case entirely.

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