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

With no annotations, the description carries the behavioral burden. It discloses one important behavior—story titles are discarded, so the output is count-only—and implies live data via 'current.' It does not mention network dependencies, caching, or response format, but for a read-only count tool this is a minimal viable disclosure.

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 short sentences communicate the action, resource, and output limitation with no filler. The key behavior is front-loaded and every word 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 simple no-required-parameter count tool, the description is nearly sufficient: it names the input domain and clarifies that titles are not returned. It would be slightly stronger if it explicitly stated the return format, but 'Count' plus 'Titles discarded' makes an integer count obvious enough.

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 provides 100% description coverage for all nine optional parameters, so the schema handles the parameter documentation. The tool description adds no meaning about which parameters actually affect the HN count or whether all of them are ignored, which is a gap given the unrelated-looking schema fields.

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 names a specific action ('Count') and a specific resource ('current Hacker News front-page stories'), making the tool's job unambiguous. 'Titles discarded' further clarifies that the result is only a count, distinguishing it from fetching or reading the stories.

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?

Usage is implied by the verb: use this tool when a caller needs the current Hacker News front-page story count. However, it does not explicitly state when to avoid it or name an alternative sibling, such as web-fetch, for retrieving actual story data.

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