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

Beyond the annotations (read-only, idempotent, open-world), the description discloses latency (bundlephobia's first measurement can take 5-30s), graceful degradation (partial failures return with sources_failed listing timeouts), and the composite nature with a detailed output summary. It even mentions that the rest still returns, which is behaviorally valuable and not covered by 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?

Though dense, every sentence carries essential information: purpose, sources, use cases, output structure, latencies, ecosystem scope, and failure behavior. It is front-loaded with the core purpose and structured logically, earning its length for a composite tool.

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?

With no output schema, the description fully explains return values (summary fields, per-advisory detail, links, alternatives). It covers edge cases (first measurement latency, timeout handling), ecosystem limitations, and the composite fan-out design, making it complete for the tool's complexity.

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, so the baseline is 3. The description reinforces 'npm ecosystem only' and mentions 'is_latest' in output, but it does not add new parameter-level meaning beyond what the schema states.

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 the tool's purpose: a composite check for adding an npm package, combining license, advisories, version history, bundle size, dependency count, and ESM/tree-shaking support from two named sources. It distinguishes itself from all sibling tools by its specific domain (npm dependency vetting) and composite nature.

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 when to use: whenever an agent asks about safety, popularity, size, or cost of adding a package. It also provides a direct exclusion for non-NPM ecosystems, directing users to 'deps.dev:version directly' for PyPI/Maven/Cargo/Go, fulfilling the 'when-not-to-use' criterion.

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