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

The annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), so the description is not the sole source. It does add genuinely useful non-schema context: the 10-credit Tier 1 cost and the default 7-day lead time. It says nothing about what the webhook payload contains, delivery retries, or how to remove an existing subscription — notable gaps for a non-idempotent registration call.

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 single prose sentence is front-loaded with the action and resource, and the bracketed metadata lines (group, endpoint, required, cost) are easy to scan. Slight credit loss because the endpoint/required lines duplicate structured schema information rather than adding new meaning.

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 the cost disclosure covers the billing concern. Still missing for a registration tool: the lifecycle story (how to list or delete a webhook, given siblings like astroway_webhooks_id and astroway_webhooks_subscribe exist) and any note on payload shape or failure handling.

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 67%, and the two documented parameters (`fields`, `precision`) are described as shaping the "compact mode" response rather than explaining how they shape webhook deliveries — a connection the description never makes. The required `url` parameter has no description at all in the schema, and the description's "[Required: url]" merely restates the schema's required array without adding validation or callback-expectation detail.

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 a specific verb and resource ("Subscribe to upcoming eclipse alerts") and the endpoint line confirms this is a webhook registration. It does not distinguish itself from the closely named streaming siblings astroway_stream_eclipse_incoming and astroway_stream_eclipse_totality, which an agent could easily confuse with this push-based alternative.

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?

"Upcoming eclipse alerts (default 7 days before)" implies the usage context and lead time, so an agent can infer this is for future-event notification rather than live data. However, there is no explicit statement of when to choose a webhook over the eclipse streaming tools, and no mention of prerequisites such as a reachable callback URL.

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