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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint=false. The description adds behavioral detail about partial failures: bundlephobia's first measurement can take 5-30s, and sources_failed will list it if it times out. This goes beyond annotations but does not describe the full retry or caching behavior.

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 relatively long but every sentence adds value. It is front-loaded with the main purpose. Minor redundancy: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly' could be slightly tightened, but overall good structure.

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 no output schema, the description comprehensively lists return fields: summary block (is_latest, license, published_at, advisory_count, bundle_kb_min, bundle_kb_gz, dependency_count, has_esm, tree_shakeable), per-advisory detail, links, and recent alternative versions. It also covers edge cases like partial failures and timeouts. Complete for a read-only composite 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%, but description adds meaning: it clarifies that scoped packages (e.g. '@types/node') are accepted for the 'package' parameter, and explains that 'version' defaults to the latest published version when omitted. This adds practical context beyond the schema.

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 it is a composite 'should I add this npm package' check combining deps.dev and bundlephobia. It specifies the verb ('scan'), resource ('dependency'), and outcome (license, advisories, bundle size). It distinguishes from sibling tools by explicitly scoping to npm packages only, with mention of NPM ecosystem.

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".' It also states what it does NOT cover (PyPI, Maven, etc.) and gives fallback guidance (use deps.dev:version directly for others). This provides clear when-to-use and when-to-avoid context.

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