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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that it returns a profile bundle including PII-adjacent fields (email, headshot) and recent articles, but says nothing about pagination, rate limits, auth, or whether the URL must resolve to an existing author. With annotations carrying the safety burden, 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?

Three short sentences, zero filler. Purpose and returned fields are front-loaded, with routing guidance following. 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-parameter, read-only tool with an output schema (so return values need no explanation) and annotations covering safety, the description is nearly complete. The minor gap is no guidance on what happens if the URL is invalid or the author has no recent articles.

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% and the single parameter is documented as 'Canonical NZ Herald author URL'. The description implies the URL identifies one author but adds no format, syntax, or example beyond what the schema states. Baseline 3 is correct when the schema already documents the only parameter.

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 uses a specific verb (Fetch) on a specific resource (one NZ Herald author's public profile) and enumerates the returned fields (name, job title, location, biography, headshot, email, recent articles). This distinguishes it cleanly from the sibling article and news tools without needing to open the 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 routes the agent explicitly: 'Use nzherald_article for one story's content. Use nzherald_news for current outlet feeds.' Two named alternatives with their distinct roles, though it does not state an explicit when-not-to-use-this condition beyond those contrasts.

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