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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint as true, and destructiveHint as false, making the safe, non-destructive nature clear. The only behavioral addition in the description is the default 'night_only=true' setting, which is useful but minor. No contradictions with annotations.

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 description is two sentences long, very concise, and front-loads the main outputs. However, the second sentence about night_only could be integrated more smoothly.

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?

The tool has a moderate parameter count (5) with an output schema, and annotations are fairly complete. The description covers core outputs but omits details on how to interpret Kp values, what 'next potentially visible satellite pass' means, and format of asterisms. With an output schema existing, return structure explanation is not needed, but usage context is still sparse.

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?

The input schema already defines all five parameters with descriptions, achieving 60% coverage. The description only mentions 'night_only' explicitly (its default), adding no detail on lat, lng/lon aliasing, or lang. It does not compensate for the 40% of schema parameters lacking 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?

The description lists specific outputs: 'Kp + next potentially visible satellite pass + First Skies asterisms', clearly naming the key resources returned. It also mentions the default night_only parameter, adding useful scope. However, it does not differentiate from sibling tools like 'aurora', 'iss_passes', or 'first_skies', which may overlap.

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 provides no guidance on when to use this tool versus alternatives. It does not mention any prerequisites, typical use cases, or when not to use it. With many sibling tools covering related astronomical topics, this is a significant gap.

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