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

With no annotations, the description must fully disclose behavior. It only states that the data is 'current' but does not mention update frequency, data source, limitations, or any other behavioral traits. This is insufficient for an agent to understand the tool's characteristics.

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 a single sentence that is concise and front-loaded. It contains no unnecessary words or information, and every part contributes to understanding the tool's purpose.

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, no annotations), the description is adequately complete. It states exactly what the tool provides. A slightly higher score would require more detail on the output format or update cadence, but for a basic current-status tool, this is sufficient.

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, and schema description coverage is trivially 100%. The description does not need to add parameter semantics since there are none. The baseline for no parameters is 4, and the description meets that expectation.

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 clearly states the tool provides 'Current planetary K-index and geomagnetic storm conditions.' The verb 'Current' combined with the specific resource 'planetary K-index and geomagnetic storm conditions' makes the tool's purpose precise. Among siblings like 'space_weather' and 'aurora_forecast', this tool is well-distinguished by its focus on K-index.

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 its siblings. It does not specify any context, prerequisites, or exclusions. The agent is left to infer usage on its own.

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