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 useful context that the source is a 'public feed' (no auth implied) and that it returns headline items from the general stream, but says nothing about pagination, volume, or refresh behavior.

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 sentences, front-loaded with what the tool does and then the routing rules; each sentence carries distinct value. Slightly long with three sibling references, but nothing is wasted.

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 no prose, and the annotations cover the safety profile. The description fully covers the routing an agent needs before calling this tool.

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?

Zero parameters, so the schema gives no parameter semantics to document and the description correctly adds none. Baseline 4 applies for a param-less tool.

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'), resource ('ABC News top stories'), and scope ('general top-story stream'), distinguishing it from abcnews_headlines, abcnews_sections, and abcnews_article. An agent can identify this as the default top-stories feed 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: section-specific lists go to abcnews_headlines, slug discovery to abcnews_sections, and single-article bodies to abcnews_article with a returned URL. The when-to-use and when-not-to-use conditions are all present.

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