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

The description adds significant behavioral context beyond the annotations: it is a composite fan-out call, partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed lists timeouts. These details are not available in the annotations and are valuable for the agent to set expectations correctly.

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 moderately long but every sentence serves a distinct purpose: purpose identification, usage scenarios, return fields, ecosystem limitation, and failure behavior. It is front-loaded with the most important information and remains well-structured, though it could be slightly streamlined without losing clarity.

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?

With no output schema, the description properly enumerates the summary block fields, per-advisory detail, links, and alternative versions. It also covers edge cases like non-NPM ecosystems and timeouts, ensuring the agent has a complete picture of what to expect and how to handle partial failures. This is comprehensive for the tool's complexity.

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 input schema already provides 100% coverage for both parameters, including scoped package acceptance and version defaulting. The description reinforces this by mentioning 'npm package' and 'version' but does not add new semantic detail beyond what the schema already offers, so the 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 clearly states the tool's purpose as a composite 'should I add this npm package' check that fans out across deps.dev and bundlephobia. It uses specific verbs like 'scan' and 'check' and enumerates concrete outputs (license, advisories, bundle size, ESM support), making it easily distinguishable from sibling research tools.

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 when to use the tool ('is X safe / popular / small' or 'what does adding lodash cost me') and provides an exclusion for non-NPM ecosystems, directing users to deps.dev:version directly. This clear when-to-use and when-not-to-use guidance goes beyond typical descriptions.

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