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

Annotations already indicate readOnly=true, idempotent=true, non-destructive. The description significantly adds behavioral context: composite fan-out across two services (deps.dev and bundlephobia), potential 5-30s delay for new version measurements, graceful degradation with sources_failed list, and return structure (summary, advisories, links, alternatives). No contradiction with annotations.

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 comprehensive but somewhat verbose; however every sentence adds value. It front-loads the main purpose with a bold claim ('Composite check in ONE call'). The structure flows logically: purpose, use case, returns, limitations, failure handling. Could be slightly tighter, but not overly bloated.

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?

Despite no output schema, the description enumerates the return fields (is_latest, license, published_at, advisory_count, bundle sizes, dependency_count, ESM/tree-shake support, per-advisory detail, links, alternative versions). It also explains partial failure and sources_failed. This provides sufficient context for an AI agent to understand what the tool returns and how to handle edge cases.

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?

Input schema describes both parameters with 100% coverage. The description adds value by clarifying that package is an npm name (with scoped package example), and that version defaults to latest. While schema already states this, the description reinforces and provides context about the default behavior and scoped packages.

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 explicitly states the composite purpose: checking npm package safety, popularity, size, and cost in one call. It uses specific verbs like 'scan', 'fans out', 'returns', and lists concrete aspects (license, advisories, bundle size). It distinguishes from sibling tools by focusing on npm dependency evaluation, a unique niche among the listed siblings.

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?

The description provides clear usage guidance: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' It also notes ecosystem limitations (NPM only in v1) and provides fallback alternatives (deps.dev:version for other ecosystems). Partial failure behavior is explained, guiding expected behavior.

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