apple_calendar_update_event

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

Annotations already convey destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds little beyond that, but clarifies the scope ('existing local Calendar.app event'). It doesn't contradict annotations, and the existing annotations carry the primary safety information.

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 concise sentences, front-loaded with the main purpose. The second sentence adds actionable guidance. No wasted words.

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 mutation tool with 8 parameters and no output schema, this description is sparse. It lacks essential context such as whether all fields are required or only provided fields are updated, what happens on success/failure, and how to handle time zone or allDay interactions. The prerequisite note helps, but overall completeness is low.

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 only 13% (only 'calendar' has a description). The description compensates minimally by explaining that uid comes from apple_calendar_list_events, but it does not add semantics for start, end, title, allDay, location, or notes. It also doesn't clarify whether the update is partial or full replacement, which is critical for correct usage.

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 clearly states the verb and resource: 'Modify an existing local Calendar.app event.' This distinguishes it from sibling tools like create and delete, and specifies the domain (Calendar.app). The additional instruction to obtain the uid from apple_calendar_list_events reinforces the purpose.

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?

The description provides a clear prerequisite: 'Obtain the uid from apple_calendar_list_events.' This implies the appropriate workflow and when to use this tool (for existing events). It doesn't explicitly mention alternatives like create/delete, but the context is clear enough.

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