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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does reveal one behavioral trait—'Titles discarded'—but it does not mention network dependency, error behavior, caching, or whether the optional parameters affect the count. For a tool that likely fetches live web data, this is a significant transparency gap.

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?

The description is extremely concise, with two short sentences and no filler. The core operation is front-loaded, and 'Titles discarded' earns its place by setting a clear expectation about the output. Nothing extraneous is included.

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 tool with no output schema and no annotations, the description should explain return values and clarify the role of the many optional parameters. 'Count ... stories' implies a numeric result, but the agent gets no guidance on whether to pass parameters, what the response looks like, or what happens if the fetch fails. The nine-parameter schema makes the lack of contextualization more costly.

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 input schema has 100% parameter description coverage, so the baseline is 3 even though the tool description itself adds no parameter-specific meaning. The description does not clarify which, if any, of the nine optional parameters are relevant to the HN count, but the schema already documents each parameter individually.

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 states the exact operation: counting current Hacker News front-page stories. It also adds 'Titles discarded', which usefully clarifies that the result is just a count and not a list of titles. However, it does not explicitly distinguish this tool from siblings such as web-fetch or fetch-status, so it stops short of a perfect score.

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?

There is no guidance on when to use this tool versus alternatives, nor any exclusions. The 'Titles discarded' hint implies a limitation but does not tell the agent when this tool should or should not be selected. The description lacks any context about prerequisites, alternatives, or conditions.

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