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

Annotations already indicate read-only, idempotent, open-world behavior. The description adds valuable context beyond annotations: partial failures degrade gracefully, the bundlephobia first measurement can take 5-30s, and the sources_failed field lists timeouts. This clarifies expected runtime behavior and failure handling, which is especially useful for an agent deciding whether to invoke the tool.

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 concise for its content: each sentence adds distinct value—purpose, when to use, return structure, ecosystem scope, and failure mode. It is well-structured with a clear opener and logical flow, and avoids redundant fluff or repetition of schema details.

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 having no output schema, the description fully enumerates the return fields (is_latest, license, published_at, advisory_count, bundle_kb_min, bundle_kb_gz, dependency_count, has_esm, tree_shakeable, per-advisory detail, links, alternative versions). It also covers ecosystem limitations, timeout behavior, and partial failure, making it sufficient for an agent to decide on invocation and interpret results.

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 schema already documents both parameters fully. The description does not add new parameter-level details beyond what the schema provides (e.g., version defaults to latest, scoped packages accepted are already in the schema). It provides context in the overall narrative but not additional syntax or format specifics, so the baseline score of 3 applies.

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 opens with a specific, actionable definition: "Composite 'should I add this npm package to my project' check in ONE call." It clearly identifies the resource (npm package) and the main action (checking licenses, advisories, bundle size, etc.), and distinguishes it from any sibling tool by its unique composite nature across deps.dev and bundlephobia.

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: "Use whenever an agent asks 'is X safe / popular / small' or 'what does adding lodash cost me'." It also provides a clear exclusion for non-NPM ecosystems ("PyPI / Maven / Cargo / Go fall under deps.dev:version directly"), serving as an alternative for those cases. It stops short of naming a specific sibling tool but gives actionable guidance.

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