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

With no annotations, the description still discloses the cost, payment currency and chain, the absence of auth requirements, and what each result contains (points, comments, links). That covers the behavioral facts an agent most needs before paying for a call; it omits nothing critical, though error/refund behavior is unstated.

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?

Front-loads the payment flag, then resource, ordering, fields, price and auth, with no filler. The trailing URL is compact and the whole entry is one scannable block.

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 two-parameter read tool with no output schema, the description supplies what the schema doesn't: cost, chain, auth posture, and return contents. Remaining gaps (rate limits, failure handling) are minor for this complexity.

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 both parameters are already documented, so a 3 is the baseline. The description echoes the sort alternative ('newest first (or sort=top)') but adds no new detail on 'n' beyond what the schema range says.

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?

States a specific resource and topic: Hacker News stories about 'javascript', with sortable ordering and returned fields. Among the many buy_hn_<topic> siblings, the topic name in the description is what pins down which one to call. It does not explicitly distinguish itself from the generic buy_hn, which keeps it from a 5.

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?

Gives useful preconditions (paid, $0.01 USDC on Base, no account or API key) and notes the sort option, but never states when to use this versus buy_hn for general queries or another topic sibling. Usage is implied by the topic label rather than spelled out.

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