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

Even though annotations declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, the description adds significant behavioral detail: 'Partial failures degrade gracefully — bundlephobia's first measurement on a new version can take 5-30s; sources_failed will list it if it times out.' It also discloses the return structure, going well beyond the annotation hints.

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 moderately long but every sentence carries value, front-loading the purpose and usage. The return format list is dense but justified by the tool's complexity; no fluff or repetition of schema details.

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?

There is no output schema, so the description must explain return values; it does so thoroughly with the summary block fields, per-advisory details, links, and alternatives. It also covers limitations, latency, and failure behavior, making it complete for an agent to invoke correctly.

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 are documented). The description reinforces that package is an npm package and clarifies NPM-only scope, but it doesn't add substantive meaning beyond the schema fields. Baseline 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 clearly states a specific verb ('check') and resource ('npm package'), and defines it as a composite check across deps.dev and bundlephobia. It includes concrete use cases ('is X safe / popular / small') and differentiates from siblings by focusing exclusively on npm dependency analysis.

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?

Explicit when-to-use guidance is provided ('Use whenever an agent asks...'), along with a clear exclusion ('NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly'). This tells the agent exactly when to choose this tool and what alternative to use.

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