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

With no annotations, the description must carry the full behavioral burden. Listing the data fields implicitly signals a read-only registry lookup, and calling out 'deprecation' and 'weekly downloads' tells the agent this is advisory data, but nothing addresses registry availability, failure for unpublished packages, or whether the response covers only the latest version.

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 sentences, both front-loaded with the resource and the use case respectively. The field enumeration is dense but adds scannable value instead of filler. Slightly list-heavy but nothing is wasted.

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 the description needn't explain return values — and the field list partially duplicates that. The real gap for a single-parameter tool is input format and failure behavior, neither of which is covered. Adequate but with a clear remaining hole.

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% for the single required `package` parameter, and the description never states the expected input form. It doesn't clarify whether scope prefixes (`@scope/name`) or version specifiers (`express@4`) are accepted — a real ambiguity for npm-style identifiers that the schema leaves entirely blank.

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 names a specific resource (an npm package) and enumerates exactly what is retrieved: version, license, repository, dependencies, TypeScript types, size, publish dates, deprecation and weekly downloads. It is missing an explicit verb, but the resource and field list make the operation unambiguous. It does not distinguish itself from the closest sibling (pypi_package), leaving that inference to the agent.

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?

"Use to choose or audit a JavaScript dependency" gives a concrete decision context rather than a generic 'gets info' statement. No exclusions or named alternatives are provided, so it falls short of a 5, but the intended use case is clear.

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