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

Annotations cover the safety profile (destructiveHint=true, idempotentHint=true, openWorldHint=true), and the description adds genuinely new behavioral detail: resource_ids replaces the entire list rather than appending, empty string clears notes/custom fields, and date/resource changes may trigger notifications. It does not contradict the destructive hint, but it also does not reconcile the partial-update framing with the destructive flag or mention failure behavior.

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?

One dense paragraph, front-loaded with the WRITE marker and partial-update rule, followed by replacement/clearing rules and then side effects. Every clause conveys a distinct constraint; nothing is repeated or padding.

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?

No output schema exists and this is an 11-parameter mutation with nested objects, yet the description covers the critical semantics an agent needs to call it safely. Remaining gaps are error/validation behavior for invalid resource ids and confirmation of the return shape, which are modest for a partial-update endpoint.

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 the baseline is 3; the description earns a bump by foregrounding the non-obvious mutation semantics (list replacement, empty-string clearing) that are the easiest things to get wrong. It adds little beyond what the schema descriptions already state, and none of the 11 parameters' valid ranges are discussed.

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?

Opens with an explicit verb+resource pair ("change fields of an existing event") and immediately qualifies scope as partial-update semantics, which cleanly separates it from scheduleit_create_event and scheduleit_delete_event. An agent can select this tool without opening the schema.

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?

Clear context for use: fields not passed remain unchanged, and empty strings are the explicit clearing mechanism. It stops short of naming alternatives (e.g. get_event to inspect before updating) or stating preconditions, so no exclusions are offered.

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