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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, and openWorldHint=true, so the mutation/open-world profile is covered. The description adds event semantics and a credit cost, but says nothing about delivery method, what happens on duplicate registration (relevant given idempotentHint=false), or rate/limit behavior.

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 short, front-loaded lines with no filler; the trigger condition comes first and the group/cost metadata is compact. Nothing is wasted, though it is arguably under-specified rather than tight.

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?

An output schema exists so return values need not be explained, but for a webhook registration tool the description omits what registration actually does, delivery expectations, and how the required URL is used. Adequate as an event label, incomplete as a tool definition.

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 67%: fields and precision are documented in the schema, but the required 'url' parameter has no description anywhere, and the description does not compensate. With a required, undocumented parameter, this falls below the baseline-3 case.

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?

The description names the concrete event ('any tracked planet ingresses a new sign'), which cleanly distinguishes it from sibling webhooks like retrograde_start, eclipse_alert, and void_of_course_start. However, it never states the action the tool performs — that it registers a subscription to a URL — leaving that to the title.

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?

There is no guidance on when to choose this webhook over astroway_stream_ingress or other streaming/webhook siblings, nor any prerequisites (auth, URL requirements, duplicate registration). The only implicit signal is the event name itself.

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