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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. Beyond that, the description contributes a real constraint not encoded anywhere in the schema: the date range is capped at 31 days. It does not cover how recurring or all-day events are handled, so it falls short of a 5.

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 short sentences, front-loaded with the resource and scope, then the differentiating detail, then the hard limit. No filler and nothing repeated from the title or schema.

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 two-parameter read tool with full schema coverage and a non-open-world annotation, this covers scope, the title-vs-busy distinction, and the range cap that an agent must respect to avoid errors. Absent an output schema, a brief note on result ordering or handling of recurring events would have made it fully complete.

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% and both date parameters carry ISO format and pattern constraints, so the schema does the heavy lifting. The description adds only the aggregate notion of a "date range" without extra semantics per parameter, which is the expected baseline.

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?

States a specific verb and resource ("List ... calendar events") and narrows the scope to the household's SHARED events, which immediately separates it from personal or availability-block reads. The parenthetical contrast with time-only busy blocks further distinguishes it from a sibling enumerator.

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 clause "Titles are returned (unlike time-only busy blocks)" gives a clear discriminator for choosing this tool over a busy-block listing. It stops short of naming the alternative tool explicitly or stating when not to use it, keeping it below a 5.

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