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

Beyond the read-only/idempotent annotations, the description discloses partial failure behavior, the 5-30s first-measurement latency for bundlephobia, the sources_failed field, and that the rest of results still return. This adds significant behavioral context not available in 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 dense but well-structured, leading with the core purpose, then usage, then behavior. The long list of return fields is justified because there is no output schema, but the sentence is somewhat long and could be broken up for easier parsing. Still, every sentence earns its place.

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 composite tool with no output schema, the description thoroughly covers the returned summary fields, per-advisory details, links, alternative versions, failure semantics, latency, ecosystem scope, and alternative tool usage. No significant gaps remain.

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% (both package and version are described), so baseline is 3. The description adds the constraint 'NPM ecosystem only in v1', clarifying that the package parameter must be an npm package, and provides a concrete example ('lodash') that helps ground the version parameter. But most parameter meaning is already in the schema.

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 a specific verb+resource: a composite 'should I add this npm package to my project' check. It distinguishes itself from sibling tools by naming the two data sources (deps.dev and bundlephobia) and the exact question it answers.

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?

Provides explicit when-to-use guidance: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. Also clearly states exclusions/alternatives: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly.'

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