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

Goes well beyond the annotations by disclosing composite behavior (fans out to multiple services), partial failure degradation, and timing (bundlephobia's first measurement can take 5-30s). It also explains what happens on timeout (sources_failed lists it). No contradiction with readOnlyHint/openWorldHint/idempotentHint.

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 adds distinct value: purpose, use case, return value structure, ecosystem scope, and failure behavior. It is front-loaded with the core purpose and well-structured.

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?

Given there is no output schema, the description fully explains return values (summary block fields, per-advisory detail, links, alternative versions). It also covers ecosystem limitations, partial failure behavior, and timing constraints, making it complete for an agent to correctly invoke and understand 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?

Schema description coverage is 100% (both 'package' and 'version' already have detailed descriptions, including scoped package acceptance and default-to-latest). The description adds no extra parameter-level meaning beyond the schema, meriting baseline 3.

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 a specific purpose: a composite 'should I add this npm package' check that fans out across deps.dev and bundlephobia for licenses, advisories, size, and tree-shaking. It distinguishes itself from alternatives by explicitly scoping to NPM ecosystem in v1 and noting that other ecosystems fall under deps.dev:version directly.

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?

Provides explicit usage conditions: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also gives clear exclusions: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly', guiding the agent to alternative tools for other ecosystems.

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