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

With no annotations, the description carries the full behavioral burden and does add real value by disclosing the paid model: '$0.002 USDC per call, paid with x402 on Base'. It still omits what happens on payment failure, whether a failed call is still charged, rate limits, and pagination behavior beyond the maxItems cap.

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 front-loaded sentences: the capability and returned fields come first, with the payment cost as a compact trailing note. Dense but every clause carries information; the field list is slightly long but justifies itself as the only description of return values.

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?

There is no output schema, so listing title, URL, domain, points, comment count, author, time, HN link and excerpt in the description is necessary and done well. For a six-parameter, zero-required, zero-annotation tool, the main remaining gap is operational detail around payment and error handling.

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 one of the six parameters is already documented in the schema, including the mode/sort/tags enumerations and the 1-50 maxItems range. The description only restates the mode list and does not add format or interaction details beyond the schema, so the baseline of 3 applies.

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 names the resource (Hacker News stories), the two operating modes (front-page lists with the five list types, or full-text search), and the fields returned. It is specific about scope but never mentions the sibling tools hn_item and hn_user, so an agent must infer that per-item and per-user lookups live elsewhere.

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?

Usage is implied through the mode enumeration and repeated 'Search only' markers, which tell an agent that q/days/sort/tags apply only in search mode. However, there is no explicit when-to-use or when-not-to-use statement, and no routing to hn_item or hn_user for single-story or user lookups.

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