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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true, destructiveHint=false, so the safety/idempotency profile is covered. The description adds genuinely useful context the annotations lack: cost (10 credits, Tier 1), group, and endpoint. However, it says nothing about streaming mechanics (persistent connection, event cadence, what 'next stations' returns) which is the core behavioral question for a stream tool.

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 short and front-loaded: the payload summary comes first, followed by compact metadata lines. Nothing is padded. The trade-off is that the opening line is a telegraphic fragment rather than a sentence, which slightly hurts readability without wasting space.

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/endpoint metadata is present. What is missing for a real-time streaming tool is any statement of how the stream behaves or when it terminates, and there is no routing against the many retrograde/webhook siblings. Adequate but with clear gaps.

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 100%, so both optional parameters (fields, precision) are already fully documented with examples and defaults. The description adds no parameter meaning beyond that, which is the correct baseline of 3 when the schema does the heavy lifting.

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 fragment 'All planets retro state + next stations' conveys the resource and payload (retrograde states plus upcoming station dates), but there is no verb and no differentiation from the retrograde-related siblings such as astroway_webhooks_retrograde_start/end or astroway_stream_transit_alerts. An agent can guess the payload but cannot tell why this differs from the webhook retrograde tools.

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 guidance and no mention of alternatives. The sibling list contains at least four closely related retrograde/webhook tools, yet the description never says when to choose this stream over a webhook subscription or a transit-alert stream. Usage must be fully inferred from the name.

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