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

The annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is well covered. The description adds valuable behavioral detail beyond those annotations: bundlephobia first-measurement latency (5-30s), graceful partial-failure handling via sources_failed, and the specific summary fields returned. It does not fully disclose rate limits or exact failure shapes, but it clearly exceeds minimum transparency given the rich 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 dense but highly efficient: three sentences cover purpose, data sources, output format, ecosystem boundaries, latency, and failure behavior. It front-loads the core value proposition and each clause carries distinct information. No fluff or repetition of schema fields.

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 two-parameter read-only tool with no output schema, the description is unusually complete. It tells the agent the exact output fields, the failure mode, the latency caveat, and the ecosystem boundary. The absence of an output schema is mitigated by the enumerated summary block and per-advisory detail mention.

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 already 3 because both parameters are documented in the schema. The description adds meaning beyond the inline schema: it states that version defaults to latest when omitted, scoped packages are accepted for package, and it connects the parameters to the output summary via is_latest. This raises the score to 4 rather than leaving it at baseline.

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 explicitly states a composite check with a clear verb ('should I add this npm package'), names the data sources (deps.dev, bundlephobia), and enumerates the exact output fields. It distinguishes itself from the sibling scan_competitor_ai_presence and general lookups by framing the use case around npm package evaluation.

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?

It gives explicit when-to-use triggers ('Use whenever an agent asks...'), scopes the ecosystem (NPM only in v1), and tells the agent where to route non-NPM ecosystems (deps.dev:version directly). This is actionable routing guidance beyond what the schema or annotations provide.

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