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

Annotations already cover safety (destructive/openWorld/readOnly), so the description's real contribution is the event payload content and the credit-cost guarantee, both of which are useful and not encoded anywhere else. It stops short of noting that a previously registered URL is replaced or that the URL is validated against private addresses.

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?

Three sentences, each carrying distinct information: what it registers, what arrives in the event body, and the cost profile. Front-loaded and free of repetition.

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?

With an output schema present and annotations covering safety, the description covers purpose, payload, and billing, which is enough for correct invocation. The only gap is what happens on re-registration or duplicate URLs.

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% and every parameter, including the SSRF guard on url, is documented in the schema. The description adds no field-level semantics beyond that, 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 and resource ('Register a URL that receives bulk-job completion events') and scopes it to the bulk-job event family, which an agent can distinguish from the sibling webhook tools (list_webhooks, test_webhook, update_webhook, delete_webhook).

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 'instead of polling' phrasing implies when a caller would want this, but no sibling alternative or exclusion is named and no precondition for using it over test/update is given. Usage is inferable rather than explicit.

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