npm_version_downloads

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, covering the safety profile. The description adds the context of 'last week' (despite the configurable period) and the interpretive angle of version adoption, but does not disclose return structure or any API quirks. This is adequate but not exceptional.

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 description is two concise sentences, front-loaded with the action, and every word adds value. 'Shows version adoption' provides a useful interpretive note without bloat.

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 simple two-parameter read-only tool, the description conveys the essential purpose and output concept (per-version counts). Although there is no output schema, the phrasing 'broken down by version' implies the response structure sufficiently. It does not specify the exact format but is complete enough for the tool's simplicity.

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 100%: both 'name' and 'period' are described in the input schema. The description only repeats the default period ('last week') without adding extra meaning, so it does not exceed the baseline of 3 for high schema coverage.

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 uses a specific verb ('Get') and resource ('download counts broken down by version'), clearly distinguishing it from sibling tools like npm_downloads (total downloads) or npm_versions (version list). The added insight 'Shows version adoption' further clarifies the tool's unique value.

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 clearly implies the use case: retrieving per-version download statistics. However, it does not explicitly mention when not to use this tool or name alternative tools for total downloads or custom ranges, so it falls short of a 5.

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