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

Goes well beyond the annotations: it discloses that the effect is persistent and automatic ("From then on EVERY matching event ... is sent there automatically"), that personally identifying visitor data (name, email, message) leaves the system, and that the URL must be public http(s). The annotations already declare openWorldHint=true and non-idempotency; the description adds the privacy and permanence consequences an agent needs before calling.

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?

Purpose and the safety constraint are front-loaded in the first two sentences, and the event catalogue is dense but each entry earns its place. The event list is delivered as one long run-on sentence with nested parentheses, which makes it harder to scan than a structured list would be, and the trailing secret/test_webhook remarks are crammed into the same block.

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, open-world creation tool with no output schema, everything an agent needs is present: what gets sent, to which events, under what URL constraints, what is deliberately out of scope, and how to verify the result. The forward-looking behavior ("From then on") removes ambiguity about whether existing events are replayed.

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%, so the baseline is 3, but the description materially exceeds it by defining the semantics of every enum value for `events` (e.g. contact.revisited fires once per visit, site.alert is not included in "all events", booking.created means waiting-for-confirmation vs already-confirmed) — detail the schema's bare enum strings do not carry. It also reinforces `url` with the owner-provided constraint, though it adds nothing for `name` or `user_goal`.

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+resource (create a webhook that forwards the site's form, contact, payment and booking events to an outside address) and enumerates exactly what it emits. It is clearly distinguishable from delete_webhook, update_webhook, get_webhook, list_webhooks and test_webhook, which the description implicitly separates by describing creation of a persistent destination.

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?

Gives positive usage (forward events to an automation service, chat channel or owner's server), an explicit safety constraint ("only use an address the owner gave you"), an explicit exclusion (signing secrets and custom headers live in the site's Webhooks settings, never here), and a follow-up action ("Use test_webhook afterwards to send a sample"). When-to-use, when-not-to-use and the alternative tool are all covered.

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