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

The description adds behavioral context beyond the readOnly/idempotent annotations by disclosing partial failure modes: 'Partial failures degrade gracefully — bundlephobia's first measurement on a new version can take 5-30s; sources_failed will list it if it times out, the rest still returns.' It also describes the composite fan-out behavior, which is not derivable from annotations alone.

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, with the main purpose front-loaded and details about usage, exclusions, and failure modes contained in later clauses. It is longer than typical but every sentence earns its place given 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 fully details the return structure, listing summary block fields, per-advisory detail, links, and alternative versions. It also covers partial failure behavior and timeout expectations, making it complete for invoking and interpreting 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 100% coverage for both parameters, including the scoped-package acceptance and default version behavior. The description does not add any additional parameter semantics beyond the schema, so a baseline of 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 explicitly states it is a 'Composite "should I add this npm package to my project" check in ONE call' that fans out across deps.dev and bundlephobia, covering license, advisories, version history, bundle size, dependency count, and ESM/tree-shake support. It clearly identifies the tool's function and distinguishes it from sibling tools by specifying the npm ecosystem scope and the composite nature.

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?

It provides explicit usage signals: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' It also defines exclusions: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly,' giving clear when-to-use and alternative guidance.

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