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

Annotations already declare the safety/profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false). The description adds genuinely useful non-annotation context: the pricing tier (10 credits), the streaming group, and the POST endpoint. It does not disclose whether this is a persistent stream or a one-shot fetch, nor stream duration/termination behavior, so it stops short of rich behavioral context.

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 tight and front-loaded: the return content leads, followed by bracketed metadata for group, endpoint, required params, and cost. Every line carries information with no filler, though the telegraphic style sacrifices some readability.

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-value documentation is rightly omitted, and annotations plus the cost/endpoint metadata cover the operational basics. However, for a streaming POST endpoint the description never clarifies consumption model (persistent stream vs single response) or why readOnlyHint is false, leaving a meaningful gap for an agent deciding how to invoke it.

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 60%, so a baseline of 3 applies. The description only restates that latitude/longitude are required (already in the schema's required list) and adds no semantics for timezoneOffset, precision, or fields, whose meaning comes entirely from the schema descriptions.

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?

"Current planetary hour + next 24" names the concrete resource and scope (planetary hour, 24h horizon), which cleanly distinguishes it from siblings like astroway_stream_lunar_phase or astroway_stream_ingress. It lacks an explicit verb, so an agent must infer that this returns/fetches the data, but the noun is specific enough to identify the tool.

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 description states prerequisites (latitude, longitude) and cost, but gives no when-to-use guidance, no conditions for choosing it over alternative stream endpoints, and no mention of the closely related astroway_webhooks_planetary_hour_tick sibling. The agent must infer the use case entirely.

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