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

Beyond the readOnly/idempotent annotations, the description discloses important behavioral details: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed will list timeouts while the rest still returns. This adds significant operational context without contradicting 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 information-dense yet well-structured: it opens with the tool's core purpose, then usage guidance, followed by a compact list of return fields, ecosystem scope, and failure behavior. Every sentence contributes value, and the length is justified by the composite nature of the tool.

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 listing the exact fields in the summary block, mentioning per-advisory details and links, and clarifying the partial failure behavior. It covers the full scope of what an agent needs to know about 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 full descriptions for both `package` and `version`, including scoped package acceptance and default behavior. The description does not add extra parameter semantics beyond the schema, so the baseline score of 3 applies.

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 identifies this as a composite check for adding npm packages, specifying the exact data sources (deps.dev and bundlephobia) and the types of information gathered (license, advisories, bundle size, etc.). It distinguishes itself from sibling tools by scoping to the npm ecosystem and explicitly mentioning what the tool does in one call.

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 triggers ('is X safe / popular / small' or 'what does adding lodash cost me') and offers a clear alternative for other ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'). This tells the agent both when to use this tool and when not to.

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