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

Annotations already declare readOnlyHint=true and openWorldHint=true, and an output schema covers the return payload, so the safety and result profile is largely pre-supplied. The description adds useful scoping context (general top-story stream, not section-filtered), but discloses nothing about feed freshness, pagination, or rate limits, so it only marginally exceeds the structured data.

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?

Four compact clauses, front-loaded with purpose before the routing guidance. Every sentence earns its place by directing the agent to a specific sibling; no 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?

With an output schema handling return values and annotations handling the safety profile, the description only needs to establish scope and alternatives, which it does fully. An agent has everything required to call 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?

The tool takes zero parameters, which is the baseline-4 case. There are no parameter semantics to add, and none are needed.

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 ('MacRumors top stories from the public feed'), and pins the scope to the 'general top-story stream'. It explicitly contrasts with macrumors_headlines (section-specific), macrumors_sections (slug discovery), and macrumors_article (single story body), so an agent can distinguish it from every sibling without opening a 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?

Names the alternatives and the exact condition that selects each: section list -> macrumors_headlines, slug discovery -> macrumors_sections, single body -> macrumors_article. Nothing is left to inference about when this tool is the right choice.

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