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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and scope are covered. The description adds what the call yields (a byline profile plus recent article links) and that it is public data, which is useful context beyond the annotations, though it stops short of describing pagination or how many recent links come back.

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, no filler, and the scoping statement plus the alternative routing are front-loaded before any detail. 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 one-parameter read tool with an output schema and annotations covering the safety profile, the description supplies everything an agent needs: what it returns, what input form is required, and which siblings to prefer. Nothing material is missing.

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?

There is a single parameter with 100% schema description coverage ('Canonical XDA author URL'), so the schema does the work and the baseline is 3. The description restates 'canonical author URL' but adds no format, example, or guidance on what makes a URL canonical versus a section or article 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?

States a specific verb (Fetch) and resource (an XDA author's public byline profile and recent article links), plus the input that identifies it (canonical author URL). It explicitly distinguishes itself from the two nearest siblings, xda_article and xda_headlines, so an agent can pick it 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?

The second sentence is pure routing: use xda_article for a single story's content, xda_headlines for outlet-wide cards. That 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.