Get 3-day planetary K-index forecast

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

With no annotations, the description carries full burden. It discloses the output format (one row per 3-hour period, UTC time, predicted Kp, NOAA G-scale if threshold) which is the key behavioral trait. It does not mention data update frequency or read-only nature explicitly, but those are less critical for a forecast retrieval 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?

Two sentences, highly efficient. The first sentence front-loads the return content and format; the second provides usage context and sibling differentiation. Every word adds value.

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?

Given the tool's simplicity (no parameters, no output schema), the description provides a complete picture: source, forecast horizon, row granularity, columns, and usage cues. Nothing essential is missing for an agent to invoke this correctly.

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 tool has zero parameters, so the baseline is 4. The description adds no parameter information because there are none; there is nothing more to explain. The schema is already empty and fully covered.

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 specifically states the tool returns NOAA/SWPC's 3-day-ahead planetary K-index (Kp) forecast table, with explicit mention of row structure and columns. It also distinguishes itself from sibling get_solar_indices, making the purpose clear and 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?

It provides explicit when-to-use guidance with example queries ('upcoming geomagnetic activity', 'will there be a storm this week') and explicitly contrasts with get_solar_indices, which is current conditions only. This tells the agent exactly when to select this tool over alternatives.

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