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

With no annotations, the description carries the behavioral burden and does so unusually well: it discloses that the call is paid ($0.10 USDC on Base), that no account or API key is required, and what the payload contains. It stops short of stating whether the charge is per call or per story, or what happens on payment failure, which keeps it below 5.

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 definition is a tight block with the most decision-relevant fact ('Paid') front-loaded, followed by content, cost, and access requirements. The raw endpoint URL is arguably filler for an agent that only needs the tool name, but nothing else is wasted.

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-optional-parameter feed tool with no output schema and no annotations, the description covers cost, payment rail, auth requirements, ordering, and payload fields, which is close to everything needed to call it correctly. Only pricing granularity and error/failure behavior are left unstated.

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 description coverage is 100%, so both parameters ('n' and 'sort') are already documented, making 3 the baseline. The description only restates the default ordering and the sort=top option, adding no new meaning such as range behavior or whether 'n' caps total cost.

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 concrete resource (Hacker News stories about 'security'), the ordering (newest first, optional top), and the returned fields (points, comments, links), so the agent knows exactly what it gets. The acquisition verb is only implied via 'Paid' and the price, and no sibling (e.g. buy_hn for general stories or buy_search) is named as an alternative, keeping it out of 5 territory.

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 by the topic-scoped name plus the note that results are newest first unless sort=top, which tells the agent how to shape a call. There is no explicit when-to-use versus buy_hn, buy_search, or other buy_hn_* topic variants, and no stated exclusions.

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