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

Surpasses the annotations by adding context: fans out to multiple external sources, bundlephobia's first measurement can take 5-30s, partial failures degrade gracefully, and sources_failed lists timed-out sources. The description details latency, failure handling, and what continues to return, which is material additional context beyond the readOnly/idempotent 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 dense but front-loaded: it starts with the purpose, then when-to-use, then outputs, then limitations. Every sentence carries important information, and the structure is logical. It's longer than typical but justified by the tool's complexity, avoiding any fluff.

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?

Despite no output schema, the description explains the return format (summary fields, advisories, links, alternatives), failure behavior, latency caveats, and ecosystem limitations. For a multi-source composite tool with edge cases, this is a complete and useful description that enables correct invocation and interpretation.

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%, so the schema already documents package and version parameters. The description adds little beyond what the schema provides (e.g., it doesn't explicitly mention that package is a name or version defaults to latest beyond the schema). It does mention scope acceptance indirectly, but that is already in the schema. Therefore, 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 the tool's purpose as a composite 'should I add this npm package' check, naming the specific actions (scans deps.dev and bundlephobia) and the output (summary block, advisories, links). This distinguishes it from sibling tools and gives a specific verb+resource with concrete details.

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 guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also states exclusions (NPM only, other ecosystems fall under deps.dev directly) and behavior on partial failures (sources_failed lists timeouts). This gives clear when/when-not guidance and alternatives.

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