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 and idempotency profile is covered. The description adds genuine context the annotations lack – a recurring 24/day firing cadence and a cost of 10 credits (Tier 1) – but says nothing about auth requirements, duplicate-registration behavior, or delivery semantics.

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 firing semantics come first, followed by bracketed Group/Endpoint/Required/Cost metadata. Every line carries distinct information with no filler.

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?

For a simple webhook-registration tool, the description covers the event, cadence, endpoint, cost, and required parameter, and an output schema exists so return values need no explanation. It omits setup/auth and lifecycle details (e.g., how to unregister), which keeps it short of complete.

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%, and 'fields'/'precision' are already well documented in the schema, so the schema does the heavy lifting. The description only restates '[Required: url]' and adds no meaning for the undocumented url parameter or for how fields/precision interact with the payload.

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 – 'Fires at every planetary hour boundary (24/day)' – and the bracketed endpoint plus title make the register-a-webhook action clear, distinguishing it from the streaming sibling astroway_stream_planetary_hour_changes. It never names that sibling, but the event resource and cadence are unambiguous.

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 when-to-use, when-not-to-use, or alternative is given. Nothing routes the agent between this webhook and astroway_stream_planetary_hour_changes (the streaming equivalent) or astroway_webhooks_subscribe, so the agent must infer the choice entirely on its own.

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