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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value by explaining the push model — events are POSTed as they happen — and that delivery goes to an external https endpoint. It doesn't mention retry behavior, delivery failure handling, hook-count limits, or whether duplicate subscriptions are allowed.

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 compact sentences: what it does, how to pick an event_type, and why you'd choose this over polling. The core action is front-loaded and nothing is redundant.

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, return values needn't be described, and the description covers purpose, delivery model, and event-type guidance adequately for a 2-parameter tool. The remaining gap is lifecycle context — how to inspect or remove existing hooks (list_hooks/delete_hook) and any subscription limits.

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 would be 3, but the description earns more by enumerating concrete event types (contact_created, form_submitted, appointment_booked) and the '*' wildcard, which gives the agent real syntax guidance the schema's generic string does not. Target URL semantics are left to the schema's uri format.

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 webhook URL') and immediately explains the effect ('MightyAutomation POSTs each matching event to it as they happen'). This clearly distinguishes it from list_events and from sibling mutation tools like add_tag or create_booking_link.

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?

Explicitly says to use event_type '*' for every event and names the alternative pattern ('instead of polling list_events'), giving the agent a clear decision rule. It stops short of stating exclusions, such as when not to register a hook or how this relates to delete_hook / list_hooks.

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