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

Beyond the readOnly/idempotent hints, the description discloses important dynamic behaviors: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30 seconds, and sources_failed will list timeouts while the rest still returns. This gives the agent realistic expectations about latency and failure modes.

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 well-structured: it leads with the core purpose, then usage context, then an ecosystem exclusion, and closes with failure behavior in a compact sequence. No word is wasted, and each clause contributes to an agent's ability to use the tool correctly.

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 composite nature (two external services) and no output schema, the description carries the full burden of explaining returns and edge cases. It lists the exact summary fields, per-advisory detail, links, recent versions, and failure behavior, making it complete for a complex tool.

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% (both `package` and `version` are documented in the input schema). The description adds a small extra detail—'Scoped packages (e.g. "@types/node") are accepted'—but otherwise reiterates what the schema already states. Baseline 3 applies because the schema fully covers parameter meaning.

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 clear, specific statement: 'Composite "should I add this npm package to my project" check in ONE call' and then enumerates the exact data sources and metrics. It distinguishes itself from sibling tools by focusing on npm dependency evaluation, unlike scan_competitor_ai_presence or validate_claim.

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 says 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'—directly telling the agent when to invoke it. It also provides an alternative path for other ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'), covering both when and when-not to use it.

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