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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds meaningful behavioral context beyond that: it discloses exactly what is returned (profile, bio 'when available', total story count) and that only the first page of stories is retrieved. The 'when available' conditional and the first-page scoping are useful; it stops short of explaining pagination for further pages.

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 the returned content and followed by the disambiguation clause. Every clause earns its place with no repetition or filler.

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. The description covers inputs (slug/url), scope (first page), and sibling routing, which is everything an agent needs to invoke it correctly.

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 description coverage is 100%, so both parameters ('slug' and canonical 'url') are already documented in the schema. The description reinforces that either slug or url can be used but adds no syntax, format, or precedence detail beyond what the schema provides. Baseline 3 is appropriate when the schema carries the parameter semantics.

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 concrete verb ('Fetch') plus the exact resource ('National Post author's public profile, bio, total story count, first page of latest stories'), and names the siblings it is not (nationalpost_article, nationalpost_news). An agent can distinguish it from the other nationalpost_* tools without opening any 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?

Explicitly routes the agent: 'Use nationalpost_article for one story or nationalpost_news for the general feed.' This names the alternatives and the condition that selects each, leaving nothing to inference.

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