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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety/scope is covered. The description adds that results are 'current' (freshness signal) and that the section must be a valid public section from rnz_sections, which is useful but modest context; no return, pagination, or rate-limit detail.

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 compact clause pair with no filler; the scoping constraint and the parameter-source constraint 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?

An output schema exists, so return values need no explanation, and the single required parameter's provenance is documented. The only minor gap is absence of result-count/pagination behavior, which is a small omission for a one-param read tool.

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?

Schema coverage is 0% and the schema only declares a bare string type. The description compensates by telling the agent the value is a valid section obtained from rnz_sections, which is meaningful beyond the schema. It still gives no format examples or slug syntax, so it only partially closes the gap.

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 verb+resource ('headlines') scoped to a single public section of RNZ, and names rnz_sections as the source of the required value. It doesn't explicitly contrast with sibling rnz_news or rnz_article, so it's clear but not fully sibling-differentiated.

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 clause 'section must come from rnz_sections' establishes a prerequisite call chain, which is real usage guidance. However, it never states when to prefer this over rnz_news or rnz_article, nor any 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.