on_this_day

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

With no annotations provided, the description carries the full burden. It does disclose that results are 'top stories' ranked per year, that the date defaults to today in UTC, and that per_year controls volume, but it omits any statement about ordering, maximum volume, or the effect of min_score, so behavior is only partially characterized.

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?

Three short lines, front-loaded with the purpose and followed by the per-parameter hints; every sentence contributes. Slightly terse rather than padded, which is the right failure mode here.

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?

An output schema exists, so return values need not be explained, and the core framing is present. Still missing is any description of min_score, expected result volume across many years, and how this differs from sibling search tools for a zero-required-parameter, history-spanning query.

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 0% and three parameters exist, so the description must compensate. It adds genuine meaning for date ('MM-DD' format, UTC default) and per_year (count per year), but says nothing at all about min_score, leaving one parameter wholly undocumented.

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 first sentence states a specific retrieval action with a clear scope: top stories on a given calendar day across every year of HN history. It is distinguishable in concept from search_stories or search_recent, though it doesn't explicitly name those siblings to reinforce the contrast.

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 line 'Handy for "10 years ago today" content' implies a use case but gives no explicit when-to-use vs. when-not guidance and never names an alternative among the seven sibling tools. An agent can infer the context but must decide between this and search_recent on its own.

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