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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is well covered. The description adds useful context: the data source (GeoNet, GNS Science), no auth required, and the client-side filter behavior for volcano_id. This goes beyond the annotations without contradicting them.

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 concise and well-structured, with the core purpose stated first, followed by the optional parameter behavior and data source. Every sentence adds value, and there is no redundant or filler content.

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 (one optional parameter, no required parameters, output schema present), the description is complete. It covers the purpose, the filter behavior, the data source, and the auth requirement. The only minor gap is not detailing the exact output structure, but the output schema likely covers that.

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 schema already provides 100% coverage with a clear description of volcano_id, including the enum values and the default behavior when omitted. The description reinforces this by mentioning the optional filter and the client-side filtering, adding a small amount of context beyond the schema.

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 retrieves the current Volcanic Alert Level and aviation colour code for New Zealand's 12 monitored volcanoes, with specific examples (Ruapehu, White Island/Whakaari, Taupo). It also mentions the optional volcano_id filter and the data source, making the purpose unambiguous and distinct from sibling tools like geonet-nz.quakes.search.

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 explains the optional filtering behavior ('Optionally filter to a single volcano_id') and notes that omitting the parameter returns all 12 volcanoes. It doesn't explicitly name alternative tools or when not to use this tool, but the context is clear enough for an agent to decide when to use it.

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