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

With no annotations, the description carries the burden of behavioral disclosure. It conveys that the operation is read-only-ish ('Count current...') and that titles are discarded, which is useful. But it does not disclose network behavior, side effects, or how the unrelated optional parameters are treated, leaving significant behavioral gaps.

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 two short sentences with no filler. It front-loads the core action and adds only the significant behavioral caveat that titles are discarded.

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 description is complete for a trivial zero-parameter count, but the actual schema exposes nine unrelated optional parameters and there is no output schema. The description does not explain whether any parameter should be supplied, how the count is returned, or what 'current' means in terms of fetch behavior, so an agent is left with unresolved ambiguity.

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 coverage is 100%, so every parameter already has a description and the baseline is 3. The tool description adds no parameter-specific guidance, and it does not clarify whether the nine optional parameters are meaningful for an HN count or simply ignored, but it does not contradict the schema either.

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 opens with a specific verb and resource: 'Count current Hacker News front-page stories.' The added 'Titles discarded' clarifies that the tool returns only a count, not the story titles, which distinguishes it from a fetch or list operation. This is clearly differentiated from sibling count tools like memory-key-count and search-query-len.

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 a count of current Hacker News front-page stories is needed. However, it does not explicitly state when to prefer it over alternatives nor mention any exclusions or prerequisites, so the guidance is only implied.

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