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

Despite annotations already flagging destructiveHint=true and idempotentHint=true, the description adds the crucial mechanism: this is a full replacement where omitted fields are reset, empty category_id clears the category, and empty waiver_form_ids silently attaches ALL active forms. That is genuinely non-obvious blast-radius information an agent could not get from annotations alone. It stops short of stating permissions or whether the prior event state is recoverable.

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?

The destructive replacement rule is front-loaded in sentence two, followed by the read-first remediation, the idempotency note, and the endpoint. Every sentence carries distinct operational information with no filler.

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 destructive mutation with no output schema, the description covers the two things an agent must know: required fields and reset semantics. It does not say what the call returns or how to verify success, a minor but real gap.

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 baseline is 3, but the description adds semantic weight the schema only asserts tersely: it explains WHY five params are required (whole-event replacement) and reinforces the counterintuitive empty-array behavior. It adds framing value beyond field-level descriptions, though a little of it restates the schema.

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?

"Update an existing event" states a specific verb and resource, and the body immediately distinguishes it from sibling waiverfile_create_event by describing replacement of an existing event. The named read partner (waiverfile_list_events) further anchors its role in the toolset.

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?

It gives an explicit workflow: read the event first with waiverfile_list_events, then resend current values for fields you do not intend to change. That names the alternative tool and the exact condition for using it, leaving nothing to inference.

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