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

With no annotations, the description bears full responsibility for disclosing behavior. It only mentions that titles are discarded, implying the output excludes titles, but it doesn't state whether it's a read-only operation, what the response format is, or any rate limits or side effects. This is insufficient for a tool that likely makes network calls.

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?

The description is brief and to the point, with two sentences that each add value: the first states the purpose, the second clarifies output behavior. It is appropriately sized for a simple operation, though it could include more context without becoming verbose.

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?

Despite the tool's apparent simplicity, the description is incomplete. There is no explanation of how to use the nine parameters, what the return value looks like, or any example invocation. The schema is broad and confusing, and the description does nothing to resolve this. An agent cannot confidently call this tool correctly.

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 schema has 100% description coverage, so the baseline is 3, but the parameter descriptions are generic and seem unrelated to the tool's purpose (e.g., 'Git ref name', 'City name for a public weather hint'). The tool description adds no clarification on which parameters are relevant or how they affect the count. This makes the parameter semantics confusing and inadequate for the tool.

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 the action ('Count current Hacker News front-page stories') with a specific verb and resource. It is not a tautology and distinguishes the tool's core function. However, it doesn't differentiate it from siblings that also deal with URLs or web content, so it lacks sibling differentiation.

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?

There is no guidance on when to use this tool versus alternatives. It doesn't mention any context, prerequisites, or exclusions. The description simply states what it does, leaving the agent without direction on selecting it over similar tools like 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.