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

With no annotations, the description carries the full burden. It discloses that it queries the public npm registry (implying read-only, no auth), lists the returned metadata, and includes a cost notice ($0.02/call). While it doesn't cover error cases or rate limits, the key behavioral traits for a lookup tool are present.

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 core purpose is front-loaded, but the third sentence restates the first almost verbatim ('Use this when an agent needs to latest version, dates and metadata from the npm registry') and contains a grammatical error. The price note is useful but appended, reducing overall efficiency.

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?

Given the tool's simplicity (one parameter, no output schema, no annotations), the description covers what the tool does, when to use it, and what data it returns. It does not explain error behavior or output structure, but that is a minor gap for such a straightforward lookup.

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%, so the parameter (package) is fully described in the schema. The description adds no additional semantic detail about the parameter, so the baseline of 3 is appropriate.

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 (Look up) and resource (any package on the public npm registry) and enumerates the fields returned (latest version, description, license, homepage, publish dates). It is distinct from all sibling tools, none of which perform npm package lookups.

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 clearly states when to use the tool: 'Agents use this to check dependencies before installing or to detect newly published versions.' It does not name any alternative or exclusion, but the intended context is clear and sufficient for a simple lookup tool.

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