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

Beyond the annotations (readOnlyHint, idempotentHint, etc.), the description discloses fan-out behavior, partial failure degradation, a potential 5-30s latency on bundlephobia's first measurement, and the sources_failed field. This adds substantial behavioral context that annotations alone do not 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 longer than two sentences, but every clause earns its place: purpose, data sources, use cases, return fields, ecosystem limits, and latency caveat. It is front-loaded with the core purpose and structured logically without repetition.

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 composite tool with no output schema, the description fully compensates by enumerating returned summary fields, per-advisory details, links, alternative versions, and partial failure behavior. It also covers ecosystem limitations and latency, making it complete for an agent to invoke 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?

The input schema already provides 100% coverage of both parameters, so the description's parameter burden is low. The description does not add much beyond the schema but reinforces the package name semantics with 'npm package name' and implicitly clarifies version behavior through examples. Baseline 3 is appropriate.

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 specific verb phrase: a composite 'should I add this npm package to my project' check that fans out across deps.dev and bundlephobia. It clearly identifies the resource (npm package health analysis) and distinguishes this from sibling research tools by emphasizing the single-call composite nature.

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 usage guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' It also gives an exclusion boundary by noting NPM ecosystem only in v1 and directing other ecosystems to deps.dev:version directly, which helps agents choose alternatives.

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