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

Annotations only cover readOnlyHint and openWorldHint; the description goes well beyond them by disclosing the payment model ($0.01 USDC per successful call on Base) and the client requirement (x402-capable wallet). It also enumerates the returned fields. That is exactly the extra context an agent needs before invoking.

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 dense sentences with zero filler: capability and scope first, return fields and cost/auth constraints after. Every clause earns its place, and the most decision-relevant constraint is front-loaded.

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?

With no output schema, the description compensates by listing the returned fields (IDs, titles, scores, comment counts, links) and by covering the non-obvious cost and wallet prerequisites. An agent has everything needed to call 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?

Schema description coverage is 100%, so both parameters are already documented, and the description adds little syntax detail beyond restating the 20-item bound for maxItems. Baseline 3 is appropriate when the schema carries the parameter burden.

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 verb ('Read') and resource ('Hacker News stories') with explicit scope: up to 20 top stories or a bounded story search. It also carves out what it is not (no users, comments, profiles, hiring text), which cleanly separates it from the sibling news/data tools.

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 tells the agent how to switch modes ('omit for current top stories' vs. a search phrase) and delimits the content space it will not return. It does not, however, name an alternative tool or state when another source (e.g., arxiv-papers) should be preferred.

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