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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds valuable behavioral context: fans out across two external services, partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed lists timeouts. This goes well beyond annotations and does not contradict them.

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 multi-sentence but information-dense: purpose, use case, return fields, ecosystem limitation, and failure behavior. Each sentence contributes unique value—no fluff. It is front-loaded with the main purpose and structured logically.

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 takes on the burden of explaining return shape and failure modes. It lists the summary block fields, per-advisory detail, links, alternative versions, and the sources_failed behavior. Combined with the parameter schema, an agent has everything needed to invoke and interpret 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?

Input schema descriptions cover both parameters 100%, including that 'package' is an npm package name and that version defaults to latest. The description reinforces the same information without adding new meaning beyond the schema. Since schema coverage is high, 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 opens with a clear composite-purpose statement: "should I add this npm package to my project" check in ONE call, and specifies the two data sources (deps.dev, bundlephobia). It also explicitly scopes to NPM ecosystem in v1, distinguishing it from any generic dependency tool and from sibling tools, which are unrelated research/Pipeworx tools.

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 trigger examples: "Use whenever an agent asks 'is X safe / popular / small' or 'what does adding lodash cost me'". Also gives a clear exclusion: "NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly." This is excellent when-to-use and when-not-to-use guidance.

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