npm_compare

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the tool's safe nature is known. The description adds that it returns comparison data across specific metrics, but does not disclose response format, error behavior, or rate limits. It aligns with annotations and adds some context, but no hidden behavioral traits are revealed.

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 sentences, front-loaded with the core action and scope. Every phrase adds value, and there is no filler or redundant information beyond the acceptable repetition of the package count.

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 read-only comparison tool with one parameter, the description covers purpose, use case, and output content by listing the comparison dimensions. It is complete enough without an output schema, given the tool's simplicity and the strong annotation coverage.

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?

The schema covers 100% of the parameter with a clear description of the 'packages' array, including min/max bounds. The description reiterates the 2-5 range but adds no additional details about package name formats or invalid input behavior. With high schema coverage, a baseline score 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 uses the specific verb 'Compare' with an explicit scope of 2-5 packages and lists the comparison dimensions (downloads, version, license, etc.). This clearly distinguishes it from sibling tools like npm_package or npm_search, which focus on single packages or searching.

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 explicitly states it is 'Great for should I use X or Y? decisions,' which conveys a primary use case. It does not name alternative tools or when not to use it, but the side-by-side framing implicitly differentiates it from single-package tools. This is clear enough without explicit exclusions.

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