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

The description adds substantial context beyond the annotations. It explains the tool fans out to two external services, has a partial failure mode (bundlephobia first measurement can take 5-30s, sources_failed lists timeouts), and discloses the ecosystem limitation. It also enumerates the return fields explicitly, which is especially valuable given no output schema. No contradiction with the readOnly/openWorld/idempotent hints.

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 information-dense yet well-structured. It front-loads the main purpose, then gives usage cues, output summary, ecosystem scope, and failure behavior. Every sentence adds value; there is no fluff or repetition of schema fields. The use of dashes and semicolons makes it easily scannable despite its length.

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 tool with no output schema, the description comprehensively covers return values (summary block fields, per-advisory detail, links, alternative versions). It also addresses failure modes, timing, and ecosystem constraints. This is a complete picture for an agent to decide when and how to invoke the tool, even without structured output metadata.

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% and both parameters already have clear descriptions in the schema. The tool description does not add new semantic meaning beyond what the schema provides (e.g., 'version' defaults to latest is already in schema). It earns the baseline of 3 for schema coverage, but does not go beyond it to add extra parameter guidance.

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: 'Composite "should I add this npm package to my project" check in ONE call.' It specifies the action (check) and the resource (npm package), and details the data sources (deps.dev, bundlephobia). It distinguishes itself from sibling tools by being the only one covering dependency scanning, and the use cases ('is X safe / popular / small') reinforce its unique role.

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 guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' It also clearly states exclusions: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly,' which tells when not to use this tool and points to an alternative. This is exactly the kind of when-to-use vs. when-not-to guidance expected.

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