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

Annotations already declare readOnly=false, idempotent=false, destructive=false and openWorld=false, so the mutation profile is covered. The description adds genuine non-annotation context: deliveries use the v2 envelope and are signed with the project signing secret, which tells an agent how consumers must verify payloads. It stops short of saying whether the secret is returned at creation time.

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?

Short and front-loaded, but the opening line 'Create a webhook' duplicates the title and is immediately restated by the next sentence ('Create a webhook subscribed to...'), so not every sentence earns its place.

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?

Covers the creation act and delivery/verification behavior, but for a non-idempotent mutation with a nested payload and no output schema it omits what is returned (webhook id? signing secret?), whether duplicate URLs are allowed, and how event types map to delivery volume.

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?

Top-level schema description coverage is reported as 0%, and the description says nothing about the 'request' wrapper or the required eventTypes/name/url payload. The only parameter-adjacent sentence ('subscribed to one or more event types') restates what the schema's eventTypes description already says, so it fails to compensate for the coverage gap.

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 and resource: create a webhook subscribed to one or more event types. This clearly separates it from webhooks-list/retrieve/update/delete siblings by operation, though it never names them explicitly.

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?

No guidance on when to create a webhook versus updating an existing one, no prerequisites, no mention of what the projectId requirement means in practice. The only pointer is 'see the signing secret endpoint', which is a routing hint rather than usage guidance.

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