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

Annotations already declare readOnly/idempotent/non-destructive, so the bar for extra disclosure is met by describing graceful partial failures, the 5-30s first-measurement delay from bundlephobia, and the sources_failed field. This adds context beyond structured annotations without contradicting them.

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 dense and well-structured: purpose, usage trigger, return fields, ecosystem scope, failure behavior. Each sentence contributes useful information, though it is longer than minimal; it earns its length for a composite tool.

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 enumerates the exact summary-block fields (is_latest, license, etc.), mentions per-advisory detail and links, and covers alternative version lists. It also explains non-NPM handling and timeout behavior, giving a complete picture for invocation and result interpretation.

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 100%, with both parameters (package and version) already documented including scoped-package examples and default-to-latest behavior. The description adds no extra parameter syntax or format details that aren't already in the schema, so baseline 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 defines a composite 'should I add this npm package' check that fans out across deps.dev and bundlephobia, enumerating specific data points (license, advisories, bundle size). This verb+resource+scope specificity distinguishes it from sibling tools like entity_profile or validate_claim.

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?

Explicitly states when to use: 'whenever an agent asks is X safe / popular / small or what does adding lodash cost me'. Also gives clear exclusion: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly', directing to an alternative.

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