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

Annotations already disclose the safety profile (readOnlyHint=false, idempotentHint=false, openWorldHint=true, destructiveHint=false), so the bar is lower. The description usefully adds the cost (10 credits, Tier 1) and endpoint, which annotations do not carry. It does not, however, explain lifecycle consequences of idempotentHint=false — e.g. what happens on duplicate registration or how a webhook is later removed.

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?

The event statement is front-loaded, followed by compact bracketed metadata (group, endpoint, required, cost) with no filler sentences. Every line carries information, though the format is terse rather than explanatory.

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 need not be explained, and annotations cover the safety profile. Still, for a 3-parameter webhook registration tool the description omits practical necessities: duplicate-registration behavior, auth requirements, and how the webhook interacts with the streaming sibling. Adequate but with clear gaps.

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 already well-documented in the schema, and `url` carries only a format constraint. The description adds only '[Required: url]', which duplicates the schema's required array. It does not compensate for the undocumented `url` semantics (callback expectations, verification).

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 states the trigger event precisely ('start of every VOC Moon period'), and combined with the title 'Register VOC-Start Webhook' an agent can distinguish this from sibling webhook tools like astroway_webhooks_retrograde_start or astroway_webhooks_sign_ingress. However, the body text describes the webhook's firing behavior rather than the tool's registering action, so the core verb ('registers a webhook') is only implied.

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 when-to-use guidance and no reference to alternatives such as astroway_stream_void_of_course (streaming) or astroway_webhooks_subscribe. The agent is left to infer that this registers a persistent webhook rather than an ephemeral stream.

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