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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and open-web behavior are covered. The description usefully adds that the content is 'public' (no auth implied) and specifies what is returned ('metadata and body paragraphs'), but says nothing about rate limits, truncation, or paywalled/missing articles.

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: the fetch action and return content come first, the sibling routing follows. Nothing is padded or repeated from the schema.

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-value structure need not be described, and annotations carry the safety profile. For a single-parameter article fetch, everything an agent needs to call it correctly is present.

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?

With one parameter and 100% schema description coverage, the schema already documents the url field. The description's 'canonical story url' phrasing reinforces the format constraint but adds essentially no syntax or example detail beyond the schema text 'Canonical GB News story URL'.

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 states a specific verb ('Fetch') and resource ('GB News article metadata and body paragraphs') plus the required input ('canonical story url'). It also names the sibling tools it is not, so an agent can distinguish it from gbnews_headlines/news without inspecting either schema.

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?

It explicitly routes the agent: gbnews_headlines for story lists, gbnews_sections for section choices, gbnews_news for the general feed. This is a clear when-to-use and when-not-to-use statement with named alternatives.

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