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

The description adds significant behavioral context beyond the annotations: it warns about a 5-30s first measurement from bundlephobia, explains graceful degradation via 'sources_failed', and clarifies the NPM-only limitation in v1. This complements the readOnly and idempotent hints without contradiction.

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 every sentence earns its place: it covers purpose, usage, return structure, failure behavior, and latency in a compact, well-organized format. The use of em-dashes and semicolons keeps it scannable despite its length.

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 the lack of an output schema, the description enumerates all return fields, describes partial failure behavior, and notes the latency edge case. It also names the external services and ecosystem boundaries, making the tool's behavior fully understandable in context.

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 fully documents both parameters (package and version) with clear descriptions and an example. The description does not add any additional parameter-level semantics beyond restating the NPM ecosystem, so the baseline of 3 applies given 100% schema coverage.

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 opens with a concrete, specific purpose: 'Composite "should I add this npm package to my project" check in ONE call'. It names the exact resources (deps.dev, bundlephobia) and data points (license, advisories, bundle size, etc.), making it unmistakably distinct from sibling tools like scan_competitor_ai_presence.

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 guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also states a clear exclusion for non-NPM ecosystems and points to deps.dev:version as an alternative, which demarks when not to use this tool.

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