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

There are no annotations, so the description carries the full burden of disclosing behavior. It does reveal that titles are discarded and that the count is for the current front page, but it does not state the output format, whether a network fetch is performed, whether a feed/URL parameter is required, or how errors are handled. This is a thin disclosure for a tool with no structured safety annotations.

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. Every word earns its place, and the brevity is effective despite contributing to under-specification in other dimensions.

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 nine optional parameters, no output schema, and no annotations, the description is not complete enough for correct invocation. It never says which parameter(s) to supply or what the response looks like beyond dropping titles. An agent would have to guess whether to call with no arguments, pass an HN feed, or pass a URL.

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 all nine parameters with descriptions, so the baseline is 3. The tool description adds no explicit parameter-level meaning, though 'Titles discarded' echoes the feed parameter's 'titles discarded' and weakly hints that feed may be relevant. It never clearly maps the tool's purpose to a specific parameter among url, feed, and the others.

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 verb and resource: 'Count current Hacker News front-page stories.' The additional phrase 'Titles discarded' narrows the behavior and helps distinguish the tool from ones that would return story details. No sibling tool appears to claim this exact HN front-page counting job.

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 description implies the tool should be used when an agent needs the current Hacker News front-page story count, and 'Titles discarded' hints this is not the tool when titles are needed. However, it names no alternatives and gives no explicit when-to-use or when-not-to-use guidance, leaving usage largely implicit.

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