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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuine context beyond that: partial-update semantics ('Only the fields passed change') and the meaning of toggling active as pause/resume, which an agent could not infer from annotations alone.

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, front-loaded with the primary action, and the modifying clause is kept short. No filler or redundancy.

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 4-parameter update tool with full schema coverage, strong annotations, and no output schema, the description is nearly complete — it conveys scope, patch semantics, and the active flag's effect. Minor gap: no mention of permissions/auth or error behavior when an invalid URL or event is supplied.

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 every parameter is already documented including the enum events and the webhook_id source. The description reiterates url, events, and active at a high level and clarifies the patch behavior, but adds little parameter detail beyond the schema — baseline 3 is appropriate.

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 (change) and resource (outbound webhook) plus the exact fields it operates on (URL, events, active), including the pause/resume capability. Scope is unambiguous, though it does not explicitly name the sibling tools (create_webhook, delete_webhook, list_webhooks) it must be distinguished from.

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?

Usage is implied by the description (modify an existing webhook), and it does add a useful constraint — 'Only the fields passed change' — indicating patch semantics. However, it gives no explicit when-to-use vs alternatives guidance and doesn't tell the agent to fetch webhook_id via list_webhooks as the schema does.

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