Register Retrograde-End Webhook

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

Annotations already declare this is a non-readonly, non-idempotent, open-world mutation, and the description adds useful context: the exact trigger condition (Mercury through Pluto stationing direct) and the 10-credit Tier 1 cost. It does not disclose delivery semantics, whether duplicate registrations are allowed (consistent with idempotentHint=false), auth requirements, or how to later remove the webhook.

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 bracketed metadata lines are compact and the trigger condition is front-loaded, so there is minimal waste. The structure is terse but scannable, though the lead sentence could be rewritten to name the action first.

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, and cost/endpoint/required URL are covered. However, for a webhook-registration mutation the description omits key context: whether one registration covers all six planets or fires per planet, auth, duplicate handling, and the unsubscribe/lifecycle path.

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 description coverage is 0%, so the description must explain the single `url` parameter, but it only restates '[Required: url]' which the schema already enforces. It adds no meaning about whether the URL must be HTTPS, publicly reachable, or what happens if it fails validation.

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's lead sentence, 'Fires when any of Mercury–Pluto stations direct,' describes the triggering event rather than the tool's action, so an agent must infer from the title and '[Endpoint: POST /v1/webhooks/retrograde-end]' that this registers a webhook. It never explicitly says 'register a callback URL,' and the nearby inverse sibling astroway_webhooks_retrograde_start is never referenced.

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 use this registration versus astroway_webhooks_retrograde_start, astroway_webhooks_subscribe, or the generic webhooks manager. Nothing states prerequisites, that a URL is the callback target, or when a caller should prefer this event over the broader transit trigger.

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