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

There are no annotations, so the description must carry the behavioral burden. It does disclose two useful traits: the count is of the current front page and titles are discarded. It does not state whether the tool fetches HN itself, whether it uses a provided feed URL, or what the return value looks like, so the disclosure is only partial.

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, with the main purpose front-loaded and no redundant phrasing. Every word contributes: 'current' sets scope, 'Count...stories' states the action, and 'Titles discarded' clarifies the output boundary.

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 no annotations, no output schema, and a nine-parameter optional schema, the description is too thin to fully support invocation. An agent still cannot tell whether to pass no arguments, a feed URL, or some other parameter, nor what the counted result looks like.

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?

All nine parameters have schema descriptions, so the baseline of 3 applies. The tool description adds no parameter guidance; only the 'feed' parameter's 'titles discarded' wording aligns with the description, while many other parameters (city, zone, json) look unrelated to counting HN stories.

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 verb ('Count'), a specific resource ('current Hacker News front-page stories'), and a clear output boundary ('Titles discarded'). This is enough for an agent to distinguish it from siblings like web-fetch or fetch-status, which do different things.

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?

The intended use is implied: call this when the agent needs the number of stories currently on the Hacker News front page. However, there is no explicit when-to-use versus alternatives, no exclusions, and no mention of whether a parameter is needed to trigger the count.

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