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

The description adds substantial behavioral context beyond the annotations: it describes the fan-out to multiple sources, graceful degradation on partial failures, a potential 5-30s latency for bundlephobia's first measurement, and the sources_failed field. This is valuable information not present in the readOnly/hint 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 and front-loaded with the core purpose, followed by usage triggers, return details, scope, and failure behavior. Every sentence provides value, though the single long paragraph could be slightly more scannable with bullet points. The length is justified by the tool's complexity.

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 thoroughly enumerates the return contents (summary block fields, per-advisory details, links, alternative versions). It also covers ecosystem scope, timing, and failure degradation, making it complete for an agent to invoke and interpret results.

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 comprehensive descriptions for both parameters (package and version), covering scoped packages and default behavior. The description does not add extra parameter-level semantics beyond what the schema states, so the baseline score of 3 for high schema coverage 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: a composite check to evaluate whether to add an npm package, aggregating data from deps.dev and bundlephobia. It lists the specific data points (license, advisories, version history, bundle size, dependency count, ESM/tree-shake support) and differentiates from direct deps.dev usage by scoping to NPM ecosystem in v1.

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?

Explicit usage guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also states when NOT to use it: for non-NPM ecosystems, directing to deps.dev:version directly. This clearly distinguishes the tool's appropriate context.

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