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

Annotations already indicate readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The description adds significant behavioral context: it fans out across two external services (deps.dev and bundlephobia), mentions that bundlephobia's first measurement can take 5-30s, and explains that partial failures degrade gracefully with a sources_failed field. No contradictions.

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 a single paragraph but packs a lot of information efficiently. It is front-loaded with the purpose and key details. Minor improvement could be using bullet points for the return summary, but it remains concise and clear.

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 explains the return value: a summary block with 9 fields, per-advisory detail, links, and a list of alternative versions. It also covers partial failure behavior and ecosystem limitations. This is more than adequate for an agent to understand the tool's capabilities.

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?

Input schema has 100% description coverage, so baseline is 3. The description adds minor context (scoped packages accepted, version defaults to latest), but these are already inferrable from the schema descriptions. No extra semantics beyond what the schema provides.

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 npm packages covering license, advisories, version history, and bundle size. It uses specific verbs like 'fans out across' and explicitly answers questions like 'is X safe / popular / small' or 'what does adding lodash cost me'. This distinguishes it from sibling tools which are unrelated to dependency scanning.

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 provides explicit usage guidance: when to use (for npm packages when evaluating safety/popularity/size), when not to use (other ecosystems like PyPI, Maven, Cargo, Go, which should use deps.dev:version directly), and the behavior for partial failures (graceful degradation with sources_failed field). This is exemplary.

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