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

Annotations already declare readOnlyHint=false, idempotentHint=false, and openWorldHint=true, so the mutation profile is covered. The description adds genuinely useful context beyond that: the exact event that fires it and the 10-credit Tier 1 cost. It still omits auth requirements, payload shape, and whether duplicate registrations are allowed — notable given idempotentHint=false.

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 lines, front-loaded with the triggering condition and followed by compact group/cost metadata. Nothing is wasted, though the single event sentence is doing less than it could.

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. However, for an open-world, non-idempotent registration tool, the description leaves out how the registration behaves (delivery, dedup, auth), which is the main remaining gap.

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 well documented in the schema while 'url' relies on its uri format alone. The description adds nothing about any parameter, so with the schema doing most of the work, baseline 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 description states the trigger event (Mercury–Pluto stationing retrograde) but never says the tool registers a webhook, so the action itself is only inferable from the name and title. It does implicitly distinguish itself from astroway_webhooks_retrograde_end via 'start', but the verb+resource framing is missing.

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?

No guidance on when to register this webhook versus polling alternatives such as astroway_stream_retrograde_alerts, nor any note about prerequisites, auth, or how it relates to the retrograde_end sibling. The agent must guess the usage context.

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