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

Beyond the annotations (readOnlyHint, idempotentHint, etc.), the description adds substantive behavior: the 20-post cap, sort order, exact returned fields (title, URL, author, score, comment count), no auth requirement, and data attribution. This gives the agent practical expectations without contradicting any annotation.

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?

Three tight sentences: core function first, then use case, then return payload and auth. Every sentence earns its place, and there is no filler or repetition beyond what's needed for clarity.

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 single-parameter read-only tool with full annotations and an output schema, the description covers everything needed: resource, ordering, limit, return fields, auth, and licensing. No critical context is missing for an agent to invoke it 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 already provides a complete description of the limit parameter (1–20, default 10, sorted by submission time). The description only reiterates "up to 20 posts" and "newest first" without adding new semantics like the default value, so it stays at the baseline for full schema coverage.

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+resource: "Fetch the most recently submitted stories from Hacker News," and immediately distinguishes itself with "newest first" and the 20-post cap. This clearly differentiates it from sibling tools like hackernews.stories.best and hackernews.stories.top, which serve different story rankings.

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 gives a clear use case: "Useful for monitoring breaking tech news and community discussion before posts gain front-page visibility." This tells an agent when to pick this tool over top/best story tools, though it doesn't explicitly name alternatives or state when not to use it, so it falls just short of a 5.

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