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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds useful context beyond that: the values are public, split between editorial and RSS sources, and are the ones rnz_headlines will accept — a cross-tool dependency an agent needs to know. It does not discuss caching or freshness, but that is minor for a static enumeration.

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?

A single short sentence with no filler; the resource and its consumer relationship are both front-loaded.

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?

With an output schema present and zero parameters, the description need not explain return values or argument syntax. It covers what the tool is and who consumes its output, which is sufficient for a simple lookup; only an explicit next-step hint would improve it.

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 takes zero parameters, so the baseline is 4. The description correctly implies a parameterless enumeration and adds no misleading parameter hints.

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?

States a specific resource (RNZ public editorial/RSS sections) and its purpose as an input to rnz_headlines, so the agent can tell it is an enumeration of valid section identifiers rather than a content-fetching tool. It does not explicitly contrast itself with rnz_news or rnz_headlines, but the resource is 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?

The phrase 'accepted by rnz_headlines' implies the usage — call this to discover valid section values before calling rnz_headlines — but there is no explicit when-to-use or when-not-to-use statement, and no mention of alternatives such as rnz_news.

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