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

Annotations already declare readOnly, idempotent, and non-destructive. The description adds significant context: it fans out across deps.dev and bundlephobia, notes that bundlephobia's first measurement can take 5-30 seconds, and explains that partial failures list sources_failed. This greatly exceeds annotation-only information.

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 informative but somewhat verbose. It front-loads the composite nature and usage scenario, then lists return fields and behaviors. Could be tighter, but every sentence adds value. A solid 4.

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?

Despite lacking an output schema, the description fully enumerates the return fields (is_latest, license, published_at, advisory_count, bundle_kb_min, etc.) and explains partial failure handling. It gives the agent a complete picture of what to expect.

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 has 100% coverage for both parameters, so the description only adds minor value: it mentions scoped packages are accepted and that version defaults to latest. The schema already describes the parameters sufficiently, so the description adds marginal benefit.

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 as a composite check for npm packages, combining license, advisories, version history, bundle size, and tree-shake support. It distinguishes itself from siblings by being NPM-specific and aggregating multiple data sources in one call.

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?

Explicitly says when to use: for questions like 'is X safe/popular/small' or 'what does adding lodash cost me'. It also notes the NPM-only scope and graceful degradation on partial failures, providing clear guidance on limitations.

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