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

The description discloses critical behavioral traits beyond the annotations: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed will list timeouts. It also notes the NPM-only scope in v1. These are valuable operational details that annotations do not cover.

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 long but densely informative, with a logical flow: purpose, use cases, return value, scope, and failure behavior. It front-loads the core purpose and avoids fluff. Minor redundancy ('composite' and 'ONE call' repeated) but every sentence earns its place.

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 responsibility for explaining return values, and it does so thoroughly: lists all summary fields, per-advisory details, links, and recent versions. It also covers failure handling and latency, making it complete for a composite tool.

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% and both parameters are well-described in the input schema. The description adds some context about what 'version' means (via 'is_latest' and 'recent alternative versions') but does not materially enhance the schema's parameter explanations. Baseline 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 opens with a specific, concrete purpose: a composite check for deciding whether to add an npm package, aggregating data from deps.dev and bundlephobia. It clearly distinguishes this from sibling tools by naming the exact output (license, advisories, bundle size, etc.) and the NPM-only scope in v1.

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?

Explicitly states when to use: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also provides an alternative for other ecosystems: 'PyPI / Maven / Cargo / Go fall under deps.dev:version directly'. This is unambiguous usage guidance.

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