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

Beyond the readOnlyHint/idempotentHint annotations, the description discloses performance caveats ('bundlephobia's first measurement on a new version can take 5-30s'), graceful degradation ('sources_failed will list it if it times out, the rest still returns'), and ecosystem limitations. This is actionable behavioral context not present in 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 dense but well-structured: purpose, when-to-use, return payload, ecosystem scope, and failure behavior are all front-loaded. It's longer than average but every sentence adds critical information. Minor deduction for length, but no word is wasted.

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 specifies the return summary block fields (is_latest, license, etc.), per-advisory detail, links, and alternative versions. It also covers error/timeout behavior and ecosystem scope. This is comprehensive for a tool of this complexity.

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 have clear descriptions in the schema, so baseline is 3. The description reinforces that version defaults to latest and mentions version history as part of output, but doesn't add syntax or format meaning beyond the schema. It notes scoped packages are accepted, which is already in the schema.

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: 'Composite "should I add this npm package to my project" check in ONE call' — a specific verb (check) and resource (npm package decision) that distinguishes it from sibling tools like scan_competitor_ai_presence. It also enumerates the exact data sources (deps.dev, bundlephobia) and output types.

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 a clear exclusion and alternative: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly.'

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