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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so the safety profile is covered. The description adds real behavioral detail beyond them: the hard 366-day window limit, the ±31-day default, and that result dates are rendered in the user timezone. It omits auth/permission and pagination behavior, so not 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?

Four dense sentences, front-loaded with the core list operation before qualification details. Slight overlap with the schema on defaults and the 366-day cap, but nothing 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?

With an output schema present, rich annotations, and 100% schema coverage, the description only needs to add operational context — and it does: window limits, defaults, filter behavior, and timezone semantics. Nothing essential to correct invocation is missing.

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 100%, so both the defaults, ISO-8601 handling, and case-insensitive substring match are already documented per-parameter. The description largely restates the schema, adding only the result-timezone note, which earns the baseline 3.

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+resource (list events) plus scope: time window, authenticated user, and inclusion of subscribed/shared calendars. That scope clause distinguishes it from get_event (single event) and makes the listing intent unambiguous.

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 supplies useful operating context (defaults ±31 days, 366-day cap, filter semantics) but never says when to prefer this over siblings such as find_conflicts, get_free_slots, or render_agenda. Usage is implied rather than routed.

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