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

With no annotations, the description carries the behavioral transparency burden. It adds one useful behavioral note—titles are discarded, so only the count is returned—but it does not mention network behavior, freshness handling, or failure modes. 'Count' strongly implies read-only, but that is left implicit.

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 action front-loaded and no filler. 'Titles discarded' earns its place by clarifying that the output is only a count.

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?

The core operation is stated clearly, but there is no explicit return-type note and no explanation of whether the optional feed parameter overrides the default HN front-page source. Given nine optional parameters and no output schema, some calling conventions are left to inference.

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?

Schema description coverage is 100%, so the baseline is 3 despite the tool description adding no direct parameter explanations. The phrase 'Titles discarded' loosely aligns with the feed parameter description, but the description does not clarify which of the nine optional parameters actually affect the count.

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 clearly states a specific action ('Count'), a specific resource ('current Hacker News front-page stories'), and the output scope ('Titles discarded'). This distinguishes it from the sibling fetch and validation tools.

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 case is implied: use it when you need the current number of Hacker News front-page stories. However, it does not explicitly say when not to use it or mention alternatives such as web-fetch or fetch-status.

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