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

Annotations already declare readOnlyHint=true and openWorldHint=true, and an output schema covers the return shape, so the safety and return surface are documented outside the description. The description adds only that the article is 'public' and that body paragraphs are included, which is modest added value.

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, zero filler, with the fetch scope front-loaded ahead of the routing hint. Every clause earns 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 single-URL read tool with full annotation coverage and an output schema, the description supplies purpose, scope, and sibling routing, so an agent can call it correctly. Only the explicit precondition (URL must come from a list tool) is left implicit.

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 100% and the single url parameter is already documented as the 'Canonical RNZ news article URL'. The description's 'one public RNZ article' reinforces scope but adds no syntax, format, or constraint detail beyond the schema, so the baseline 3 applies.

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 (Fetch), a bounded resource (one public RNZ article), and the exact payload (metadata and body paragraphs), which distinguishes it from the list-style siblings rnz_headlines/rnz_news. An agent knows this is a single-item detail fetch rather than a feed.

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?

Explicitly routes discovery to rnz_headlines/rnz_news and byline lookups to rnz_author, implying this tool is for retrieving an already-identified article. The 'when to use this' direction is strong but not stated as an explicit precondition (e.g. 'call after obtaining a URL from rnz_headlines').

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