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

The description adds that it returns item IDs and usernames, and the term 'recently changed' implies a time-bound feed. It does not contradict the readOnlyHint and openWorldHint annotations, but it doesn't clarify what 'recently' means (e.g., last hour, last day) or whether there are limits. The annotations carry the read-only safety profile, so this is acceptable but not rich.

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?

A single, clear sentence that front-loads the primary purpose. No fluff, and every word adds value.

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 zero-parameter tool with annotations covering read-only and open-world behavior, the description is sufficient: it states what is returned (IDs and usernames) and the temporal scope. It could be more specific about the time window or list format, but the overall complexity is low and nothing critical is missing.

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 tool has zero parameters, so baseline 4 applies. The description doesn't need to explain parameters, and it doesn't introduce any ambiguity.

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 states a specific action ('Get') and a clear resource ('recently changed Hacker News item ids and usernames'), so an agent can tell it's a retrieval tool. However, it doesn't explicitly differentiate from siblings like hackernews_feed_list or hackernews_item_get, relying on the name to imply the update-focused scope.

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?

There is no guidance on when to use this tool versus the many hackernews_* siblings. No mention of prerequisites, use cases, or explicit exclusions, leaving the agent to infer from the name alone.

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