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

Annotations already declare idempotentHint=true, destructiveHint=true, and readOnlyHint=false, so the safety profile is largely covered. The description adds genuine value with the partial-update rule (omitted fields remain unchanged), but it does not disclose what 'destructive' means here (e.g. that eventTypes overwrites the subscription set) or any auth requirements. With annotations carrying the safety burden, a 3 is appropriate.

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?

Two tight sentences with zero waste; the affected fields are front-loaded and the optionality rule follows immediately. Nothing is padded or redundant.

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?

An output schema exists, so return values need not be explained, and the field summary plus partial-update rule cover the core call mechanics. It falls short of full completeness by omitting permission/authorization context and any caveat about replacing versus merging event subscriptions.

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%, so all five parameters, including the null-clears-name and the replaces-events semantics, are already documented in the schema. The description's field list adds only a summary and no format or constraint detail beyond what the schema supplies, so the baseline 3 applies.

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 (Updates) and resource (webhook) and enumerates the affected fields: name, URL, subscribed events, active state. This clearly separates it from create_webhook, delete_webhook, and get_webhook, though it doesn't explicitly name those siblings.

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 statement that every field besides id is optional signals patch-style usage, which implicitly tells an agent when to reach for this tool. However, there is no explicit when-to-use or when-not guidance, no preconditions, and no mention of alternatives like delete_webhook for removal.

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