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

Annotations already declare it non-read-only, non-idempotent and non-destructive, so the description needed to add the things annotations cannot express — chiefly whether supplied fields replace or merge with existing configuration, what happens to triggers omitted from the array (minItems 1), and whether rotating the secret invalidates in-flight deliveries. None of that is present; the sentence only restates the mutable fields.

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 clause, front-loaded with the verb and resource, listing the mutable fields with no preamble or filler. Nothing could be removed without losing information.

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 non-idempotent mutation with no output schema and only 33% parameter documentation, the description leaves critical operational questions unanswered: merge-vs-replace behavior, effect on existing triggers, and whether a secret change breaks signature verification for subscribers. An agent could invoke it but could not predict the consequences.

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 only 33%, so the description should compensate. It names four of the six parameters (URL, triggers, secret, active) but never mentions webhookId as the required identifier nor payloadTemplate, and it gives no semantics for how the triggers array is applied. Partial compensation justifies the baseline 3, not more.

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?

"Change an account-level webhook's ..." is a specific verb plus resource, and the qualifier "account-level" distinguishes it from the sibling update_event_type_webhook and create_webhook. It stops short of 5 because the enumerated fields are incomplete relative to the schema (payloadTemplate is omitted), so the agent's picture of scope is partial.

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 word "Change" implies mutation of an existing webhook, and "account-level" implicitly routes away from the event-type webhook siblings, but no alternative is named and no precondition (e.g. 'webhookId must come from list_webhooks') is stated. Usage is inferable rather than guided.

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