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

Annotations already cover the safety profile (write, non-idempotent, open-world, non-destructive), and the description adds real value by disclosing cost (10 credits, Tier 1) and the concrete endpoint. It does not say whether repeated registrations for the same URL create duplicates (relevant given idempotentHint=false) or what auth/permissions are required.

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?

Extremely compact and front-loaded: the trigger condition comes first, followed by tight bracketed metadata. Nothing is wasted, though the bracketed metadata style reads more like reference data than explanatory prose.

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 the essential call facts (endpoint, required param, cost, trigger) are covered. Still missing is routing guidance against the many sibling webhook registration tools and any note on auth or duplicate-URL handling for a non-idempotent write.

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%, with 'fields' and 'precision' fully documented in the schema and the description only flagging '[Required: url]'. The description adds no syntax, format, or validation meaning beyond what the schema already provides, so the baseline of 3 applies.

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 trigger condition is stated precisely ('fires when any of Mercury–Pluto stations direct') and the bracketed endpoint plus title 'Register Retrograde-End Webhook' make the action unambiguous. It is clearly distinguishable from astroway_webhooks_retrograde_start by the 'stations direct' event, though the description itself never names that sibling.

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?

The definition of the firing event implies when this webhook is relevant, which is genuine selection context. However, it gives no explicit guidance on when to prefer this over the sibling astroway_webhooks_retrograde_start or the other webhook registration tools, and no prerequisites or exclusions are stated.

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