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

Annotations already signal read-only, idempotent, open-world behavior. The description adds meaningful behavioral detail beyond annotations: composite fan-out nature, partial failure handling, the 5-30s first-measurement latency for bundlephobia, and the sources_failed field. No contradiction with 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 front-loaded with the core purpose and then efficiently covers use cases, return fields, limitations, and failure behavior. Every sentence adds distinct value; no fluff or repetition of schema/annotations.

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 no output schema, the description compensates by enumerating the summary block fields, per-advisory details, links, and alternative versions. It also covers ecosystem scope, latency, and graceful degradation, making the tool's behavior fully predictable for the agent. The tool's complexity is high, but the description leaves no significant gaps.

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%, with both 'package' and 'version' already described clearly, so the baseline is 3. The description adds context that the package is npm and that version defaults to latest, but the schema already handles that. It does not add new parameter-level details beyond 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 clearly states a specific composite check for npm packages, using a concrete question ('should I add this npm package') and explicitly naming the data sources (deps.dev, bundlephobia). It distinguishes itself from siblings by focusing on dependency/packaging risk and cost, not entity profiles or competitors.

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?

Provides explicit trigger phrasing ('Use whenever an agent asks "is X safe / popular / small"...') and exclusion guidance for non-NPM ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'). This gives the agent both when-to-use and when-not-to-use context.

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