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

Beyond the annotations (readOnly, idempotent), the description discloses fan-out behavior across multiple services, partial failure degradation (sources_failed), and timing variability (5-30s on first measurement). It also clarifies the NPM-only constraint, which is not evident from the schema. 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 well-structured and front-loaded with the core purpose. Every sentence adds value: use cases, return fields, ecosystem limits, partial failure behavior. Despite its length, it avoids redundancy and each detail supports agent decision-making.

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 compensates by enumerating return fields (is_latest, license, bundle_kb_gz, etc.), per-advisory details, links, and alternative versions. It also covers partial failure and timing, making it sufficiently complete for a complex, composite tool.

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% for both parameters (package and version). The description does not add new input semantics beyond what the schema already states—it only gives usage examples and output context. Baseline 3 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 opens with a specific verb+resource+scope: "Composite 'should I add this npm package to my project' check in ONE call," and names the exact sources (deps.dev and bundlephobia). It clearly distinguishes from sibling tools by focusing on npm dependency evaluation and explicitly stating NPM ecosystem only.

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 explicitly ties usage to user intents: "Use whenever an agent asks 'is X safe / popular / small' or 'what does adding lodash cost me'." It also provides a when-not via "NPM ecosystem only in v1" and directs non-NPM cases to "deps.dev:version directly," which serves as an alternative.

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