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

Annotations only declare readOnly/non-destructive, but the description goes well beyond that: recurring events are expanded one-entry-per-occurrence, each carries an event_ref, my_status encodes the caller's invite response (pending = unanswered), and titles/notes/locations are untrusted third-party content to be treated as data, not instructions. That trust-boundary warning is high-value context no annotation supplies.

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 dense paragraph that is front-loaded with the core behavior (scope, ordering) before defaults, filtering, recurrence handling and the safety note. Every sentence adds a fact an agent would otherwise have to guess.

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 read-only list tool with an output schema present, the description covers scope, time formats, defaults, filtering, recurrence expansion and untrusted-data handling. The only real omission is limit/pagination semantics, which is minor against an otherwise complete behavioral picture.

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 0%, so the description must carry the burden and largely does: start/end accept ISO or unix seconds, a date-only end includes the whole day, and calendar (title or id), category and query (title or location) are explained. Only `limit` is left undocumented, leaving pagination size to the bare schema default.

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 plus the exact scope: events in a time range, oldest first, across enabled calendars, with recurring events expanded. It also distinguishes itself from the follow-up tool by naming get_event and the event_ref handoff, so an agent can separate listing from detail retrieval.

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?

Gives clear usage context: default window (now to 7 days ahead) and how to narrow the result set via calendar, category or query. It does not explicitly contrast itself with the closest sibling (show_today) or state when-not to use it, so it stops short of full when/alternatives guidance.

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