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

Despite annotations already indicating read-only/idempotent safe behavior, the description adds critical behavioral context: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed lists timeouts. This goes beyond annotations to set latency expectations and failure semantics. No contradiction.

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?

Every sentence earns its place: purpose, usage trigger, return format, ecosystem limitation, and failure behavior. It is dense but well-organized, with the main purpose front-loaded and no redundant phrases. Despite its length, it remains concise relative to the complexity of a composite tool.

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 and the complexity of a two-source composite, the description covers purpose, return fields, ecosystem scope, latency, and partial failure behavior. It fully equips an agent to understand what will happen, what to expect, and when to prefer other tools. Very complete.

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%—both 'package' and 'version' already have clear descriptions. The tool description adds little beyond what the schema provides, except indirectly referencing version history and alternatives, which are return fields rather than parameters. Baseline 3 is appropriate per rubric when schema fully covers params.

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?

Description clearly states it's a composite check for 'should I add this npm package' that fans out to deps.dev and bundlephobia. Specific verb (scan/check), resource (npm dependency), and scope (license, advisories, bundle size) are all present, distinguishing it from generic research tools.

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 'Use whenever an agent asks "is X safe / popular / small"' and provides an exclusion for non-NPM ecosystems, directing PyPI/Maven/Cargo/Go to deps.dev:version directly. This gives clear when-to-use and when-not-to-use guidance relative to alternatives.

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