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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real context beyond that: the source is a public feed and the stream is the 'general top-story' one, i.e. unfiltered/top-level, which implicitly explains why section filtering must be routed elsewhere. It does not mention pagination or result limits, so it falls short of a 5.

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 short sentences that are front-loaded with the primary action and then branch to alternatives. Every sentence carries routing or scoping information; there is 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 present, return shape need not be described, and the description fully covers what the tool does, what it does not do (section-specific lists), and where to go instead. Nothing an agent needs to call this correctly 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate beyond confirming the call is argument-free, which the 'general top-story stream' phrasing implies. Baseline 4 applies for a 0-parameter 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 and resource ('Fetch CNET top stories from the public feed') and immediately scopes it ('returns headline items from the general top-story stream'). It explicitly distinguishes itself from cnet_headlines, cnet_sections, and cnet_article, so the agent can disambiguate 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?

Names the alternatives and the exact condition that selects each: cnet_headlines for a section-specific list, cnet_sections to discover slugs, and cnet_article when the story body is needed. Nothing is left to inference.

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