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

Despite annotations already declaring readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, the description goes further by disclosing partial failure degradation, the 5-30s latency for first-time bundlephobia measurements, and the sources_failed field. This operational context is not present in annotations and is essential for setting agent expectations.

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 remarkably efficient: it front-loads the core purpose, then usage triggers, return fields, ecosystem scope, and failure behavior. Every sentence serves a distinct purpose, and there is no redundancy or filler.

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?

For a composite tool with no output schema, the description enumerates the exact fields in the summary block, per-advisory details, links, and alternative versions. It also covers failure modes and latency, making it complete enough for an agent to invoke the tool correctly and interpret the result.

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?

The input schema already provides 100% coverage for both parameters with clear descriptions. The description adds an ecosystem constraint ('NPM ecosystem only') that clarifies the valid values for 'package', and it ties 'version' to the context of comparing alternatives. While not extensive, it does add meaning 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 defines the tool as a composite check for 'should I add this npm package to my project', specifying that it combines deps.dev (license, advisories, version history) and bundlephobia (bundle size, dependency count, ESM/tree-shake support). This verb-resource pairing is specific and distinguishes it from all sibling tools, none of which cover dependency scanning.

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?

The description explicitly states when to use the tool: whenever an agent asks 'is X safe / popular / small' or 'what does adding lodash cost me'. It also provides exclusion guidance, noting that the NPM ecosystem is the only supported one in v1 and that PyPI/Maven/Cargo/Go fall under deps.dev:version directly—thereby steering users to alternatives.

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