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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose one non-obvious trait—'Titles discarded'—which tells the agent that titles will not be part of the result. It does not clarify whether the tool performs a live network fetch, what the exact return format is, or how the unrelated optional inputs are treated.

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, front-loaded with the key action and resource, with no filler or repetition. Every word contributes to the agent's understanding.

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 count tool with no required parameters, the description is nearly sufficient. However, the presence of nine seemingly unrelated optional input properties creates ambiguity about whether any argument should be supplied, and there is no output schema or annotation to clarify the return shape. A sentence stating that the arguments do not affect the count would make this complete.

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 covers 100% of the nine parameters with descriptions, so the baseline is 3. The tool description adds no additional parameter-level meaning; only the phrase 'Titles discarded' partially overlaps with the feed parameter's description. Since all parameters are optional, the agent can safely call the tool with no arguments, but the description does not reinforce that.

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 a specific action ('count') and a specific resource ('current Hacker News front-page stories'), so the tool's purpose is unmistakable. 'Titles discarded' adds useful scope by signaling that the result is a count rather than a list of story titles. No sibling appears to offer the same HN front-page counting behavior.

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 usage context is implied by the verb: an agent would select this tool when a count of current Hacker News front-page stories is needed. However, it does not explicitly say when not to use it or mention alternatives such as web-fetch or fetch-status, leaving some selection guidance to inference.

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