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

Beyond the annotations (readOnly, idempotent, etc.), the description discloses important behaviors: composite fan-out, return structure, graceful degradation on partial failures, and a specific 5-30s latency risk on first bundlephobia measurement. No contradiction with annotations found.

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?

Though long, every sentence earns its place: purpose, usage, return fields, ecosystem scope, and failure handling are each covered distinctly. The structure is front-loaded with the primary purpose and progressively adds context without redundancy.

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 enumerates the return fields (summary block with exact keys, per-advisory detail, links, alternative versions). It also covers edge cases (partial failures, timeouts, ecosystem restrictions), making the tool's behavior predictable for the agent.

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 coverage is 100% (both package and version have meaningful descriptions). The description doesn't add substantial parameter-level meaning; it reiterates the 'latest' default and scoped package acceptance already present in the schema. Baseline 3 is appropriate because the schema does the heavy lifting.

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 formulation: 'Composite "should I add this npm package to my project" check in ONE call' and explicitly names the underlying sources (deps.dev, bundlephobia). It clearly distinguishes from siblings by limiting scope to the NPM ecosystem and stating what the tool aggregates.

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 given: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also provides an exclusion for non-NPM ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'), telling the agent exactly when NOT to use this tool and pointing to an alternative.

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