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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, so the safety profile is well-covered. The description adds only 'real-time' as a behavioral trait, which is a minor addition; it does not explain update frequency, latency, or data provenance. This adds some value but not substantial context beyond 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 a single short phrase 'Boulder K-index real-time', which is highly concise and front-loaded with the key term 'Boulder K-index'. It avoids filler, but is more of a label than a complete sentence. It is not overlong, yet it could be slightly more descriptive without harming conciseness.

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 description is extremely thin and fails to explain what Boulder K-index is, how it relates to the planetary Kp index, or when to use this tool over the sibling 'kp_index'. Even though the tool is simple and an output schema exists, the lack of any differentiation from similar tools makes the description incomplete for agent selection.

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 the input schema is empty, so there is no parameter ambiguity. The schema coverage is trivially 100%, and the description need not add parameter details. This is the ideal scenario for parameter semantics, as there is nothing to explain or compensate for.

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 'Boulder K-index real-time' clearly identifies the resource (Boulder K-index) and temporal scope (real-time), which distinguishes it from the sibling 'kp_index' by location. However, it lacks an explicit action verb like 'get' or 'retrieve', making it a noun phrase rather than a full tool description, and the distinction from similar siblings is implicit.

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 vs. alternatives such as 'kp_index', 'solar_wind', or 'aurora_forecast'. There is no mention of use cases, prerequisites, or situations where one should prefer this tool over others, leaving the agent without selection criteria.

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