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

The description adds rich behavioral context beyond annotations: it fans out across multiple sources, handles partial failures gracefully, notes potential 5-30s latency on bundlephobia's first measurement, and mentions the sources_failed field. These details complement the readOnly/idempotent/non-destructive hints without contradicting them.

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 every sentence earns its place: purpose, use cases, return fields, ecosystem scope, and failure behavior are all covered without redundancy. It is front-loaded with the core purpose and organized logically, making it easy to parse despite its length.

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 carries the full burden of explaining return values, and it does so thoroughly: summary block fields, per-advisory details, links, alternative versions, and failure behavior (sources_failed). It also explains ecosystem scope and fallback, making the tool's behavior comprehensive for the agent.

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%, so the baseline is 3. The description adds context around the version parameter (e.g., new versions may require a first measurement) but does not add further semantic meaning beyond what the schema already provides for both 'package' and 'version'.

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: a composite check for 'should I add this npm package to my project' in one call. It specifies the resource (npm package), the data sources (deps.dev, bundlephobia), and the scope (NPM ecosystem only), distinguishing it from sibling tools like scan_competitor_ai_presence and from direct deps.dev usage for other ecosystems.

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 usage guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also excludes non-npm ecosystems by directing users to deps.dev:version directly, giving a clear alternative and when-not-to-use.

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