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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds critical behavioral details: partial failures degrade gracefully, bundlephobia's first measurement may take 5-30 seconds, and the `sources_failed` field will list timeouts. This goes beyond the structured 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 relatively lengthy but every sentence provides necessary information: purpose, what it fans out, return shape, limitations, and failure behavior. It is front-loaded with the main purpose. Could be slightly tighter, but overall well-structured for the information density.

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?

Given the tool has two parameters, no output schema, and modest complexity, the description covers all important aspects: what it does, what it returns (summary block, advisories, links, alternatives), error handling, timing behavior, ecosystem limitations, and feature set. No gaps identified.

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 baseline is 3. The description does not add extra parameter semantics beyond what the schema already provides (package name and version). It mentions the parameters in context but no additional constraints or formatting rules.

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 is a composite check for npm packages combining deps.dev and bundlephobia, and specifically mentions the use case of answering 'is X safe / popular / small' or 'what does adding lodash cost me'. It distinguishes from other ecosystems by explicitly stating NPM-only in v1 and directing to deps.dev for others.

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 says 'Use whenever an agent asks...' and also clarifies limitations: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly.' This provides clear when-to-use and when-not-to-use guidance, differentiating from sibling tools.

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