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

The description adds significant context beyond the annotations: it fans out across two external services, reveals latency (5-30s for bundlephobia first measurement), and explains graceful degradation with sources_failed listing timeouts. It also clarifies NPM-only scope and partial failure behavior, which annotations alone cannot convey.

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 every sentence contributes: purpose, providers, triggers, return fields, ecosystem scope, and failure mode. It is longer than minimal but earns its length for a composite tool; a slight trim of the return field list would improve conciseness.

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 complex composite tool with no output schema, the description is remarkably complete. It lists the summary fields, per-advisory detail, links, alternative versions, NPM-only constraint, and performance expectations. An agent has enough to invoke and interpret results correctly.

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?

Both parameters are fully documented in the schema (100% coverage). The description restates that version defaults to latest and mentions scoped packages, but adds little new semantic value beyond what the schema already provides. Baseline of 3 is appropriate when schema carries the burden.

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 composite purpose: "should I add this npm package to my project" check in ONE call. It specifies the exact providers (deps.dev, bundlephobia) and the data points they cover, distinguishing it from any sibling tool. This is a specific verb+resource with strong differentiation.

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?

Explicit when-to-use triggers are given: "Use whenever an agent asks 'is X safe / popular / small' or 'what does adding lodash cost me'". It also provides exclusions for non-NPM ecosystems, directing to deps.dev:version directly, and notes the fallback behavior for failed sources.

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