swpc_dst_index

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

Annotations already declare readOnlyHint=true, indicating a safe read operation. The description adds interpretive context for the Dst values (e.g., thresholds for moderate/intense storms) but does not disclose specifics about the response format, time window, or data source. Thus it adds modest value beyond the 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?

Two sentences, front-loaded with the core function, and no redundant information. The second sentence provides useful interpretive thresholds in nT, earning its place.

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?

For a parameterless tool with no output schema, the description is reasonably complete, identifying the index and its units via thresholds. However, it could clarify whether it returns the current value or a time series, and the exact response shape is not described. These gaps are minor given the tool's simplicity.

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 no parameters, so the schema covers everything. Baseline of 4 is appropriate; the description's threshold explanation adds context but is not required for parameter understanding.

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's function with 'Get Dst (disturbance storm time) index', using a specific verb and resource. This distinguishes it from sibling SWPC tools like swpc_kp_index, which target different space weather indices.

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 implies usage by explaining Dst interpretation, but it does not explicitly state when to prefer this tool over alternatives such as swpc_kp_index or swpc_alerts. There is no alternative guidance or exclusions, so usage is only implied.

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