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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description does add real context beyond them, namely that adding an event triggers an on-Mac prompt, but it omits what happens when start/end are null or how the picker behaves without event_title.

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 short sentences with the main capability front-loaded and a useful caveat second. The trailing phrase 'adding asks on the Mac' is terse and slightly opaque but earns its place by flagging an interactive confirmation step.

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?

An output schema exists, so return values need no explanation, and annotations cover safety. However, for a 4-parameter tool with zero schema coverage, the description leaves the two time-bound parameters and the sibling relationship unexplained, which is thinner than the tool's complexity warrants.

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 four parameters rely on their bare titles. The description explains only event_title, leaving start, end, and duration_minutes (default 30) entirely uninterpreted, and it doesn't clarify date formats or slot granularity.

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?

Names a specific verb and resource: showing free calendar slots the user can pick from. The phrase 'the user can pick from' hints at an interactive picker, but the description never contrasts this with the closely related sibling find_free_time, so the exact distinction stays implicit.

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 explicit when-to-use or when-not-to-use guidance, and the obvious alternative, find_free_time, is never mentioned even though the two names are nearly interchangeable to an agent. Usage must be inferred entirely from the word 'show'.

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