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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and network scope are covered. The description adds the content shape of the response but says nothing about pagination of 'recent article items' or how many are returned, which is the kind of extra behavioral context that would push this higher. With annotations carrying the safety profile, 3 is appropriate.

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, front-loaded with what the tool returns and followed by the routing hint. No filler and nothing buried.

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 not be re-explained, and the read-only annotations cover the safety profile. The description tells the agent what it gets and when to prefer siblings; only the volume/pagination of recent articles is left unstated, which is a minor gap.

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 param is documented as 'Canonical News.com.au author URL.' The description's phrase 'from canonical author `url`' reinforces that it must be canonical rather than a name, but adds no format or syntax detail beyond the schema. Baseline 3 correct.

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) and resource (News.com.au staff writer's profile), then enumerates the exact payload: title, biography, social links, and recent article items. It even names the canonical `url` as the key input, so an agent can distinguish it from newscomau_article and newscomau_headlines at a glance.

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 the agent: 'Use newscomau_article for one story or newscomau_headlines for story lists,' which names alternatives and the condition that selects them. It stops short of stating when *not* to use this tool (e.g., no author-name lookup, requires a canonical URL), but the routing guidance is clear.

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