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

With no annotations, the description must carry the behavioral load. It discloses two useful traits: results are curated by notability (not exhaustive) and span multiple countries. It says nothing about result ordering, default page size, or that results are paginated via limit/offset (max 200), which matters for a curation-ranked list.

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 tight sentences: capability and scope first, then the query pattern it answers. No filler and nothing buried.

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?

A 5-parameter tool with 0% schema coverage, no annotations, and no output schema needs the description to explain the opaque genre enum and the pagination pair. Two of the five parameters are entirely undocumented anywhere, and the genre vocabulary is unintelligible without external knowledge.

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 0%, so the description must compensate. It explains year and month only via a single example and mentions genre as 'optionally one genre', but never clarifies the 31 enum values (e.g. 'kohaku', 'uslaw', 'takarazuka', 'cosme'), and says nothing at all about limit or offset.

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 verb and resource ('List the most notable items for a given year and month') and scopes it with an example (year=1985, month=8). It implicitly contrasts with on_this_day and person_timeline by being month+year rather than day or person, but never names a sibling to make the distinction explicit.

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?

It gives a clear triggering question ('what happened / what came out in <month> <year>'), which directly tells an agent the retrieval context. There are no exclusions or named alternatives, so it falls short of the 5 bar.

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