apple_calendar_set_url

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

Annotations already declare destructive, idempotent, and open-world behavior, so the safety burden is largely covered. The description adds the useful fact that the operation can clear (not just set) a URL, but it does not explain that an existing URL is overwritten, what error occurs for a bad UID, or any permission requirements.

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?

A single short sentence with the action front-loaded and no filler. Nothing in it is wasted.

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 destructive mutation with zero parameter documentation and no output schema, the description is too thin. An agent cannot tell how the event is identified (calendar + uid), whether the change is reversible, or what a clear operation returns.

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 0%, so the description must compensate. It hints that url is an HTTP/HTTPS value and that empty clears it, partially explaining the anyOf empty-string branch, but it says nothing about the calendar or uid identifiers that are required to locate the event.

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 a specific verb pair (set/clear) and a specific resource (an event's HTTP/HTTPS URL), which is distinct from calendar siblings like set_recurrence or add_alarm. It does not, however, explicitly differentiate itself from apple_calendar_update_event, which plausibly could also touch a URL.

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 update_event or the other calendar mutation tools, no prerequisites, and no indication of what happens on failure. Usage must be inferred entirely from the name and event-URL semantics.

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