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

Beyond the existing annotations (readOnlyHint, openWorldHint, idempotentHint), the description discloses important behavioral details: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed will list timeouts while the rest still returns. This adds significant context for managing expectations.

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 each sentence earns its place: purpose, use case, return structure, ecosystem limitation, and failure behavior. It is well-structured with em dashes and semicolons, front-loading the core purpose.

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?

Given the tool's complexity (composite of two external services) and no output schema, the description thoroughly covers return fields (summary block, per-advisory detail, links, recent versions), ecosystem scope, and potential delays. This is sufficient for an agent to understand what the tool does and what to expect.

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%, so the baseline is 3. The description does not add parameter-specific semantics beyond what the schema already provides (package name, version optional with default). It mentions version history and alternative versions, but these are about behavior, not parameter syntax.

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: it is a composite check for 'should I add this npm package to my project', fanning out across deps.dev and bundlephobia. It names specific data sources and categories (license, advisories, bundle size, tree-shake support), distinguishing it from other 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?

Provides explicit when-to-use guidance: 'Use whenever an agent asks is X safe / popular / small or what does adding lodash cost me'. It also contrasts with deps.dev:version for other ecosystems, giving an alternative.

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