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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive nature. The description adds substantial behavioral context: fan-out across two services, potential 5-30s delay for first bundlephobia measurement, graceful partial failure via sources_failed, and details of the return payload. No contradiction with annotations.

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 typical but well-structured: purpose first, then usage, then behavior/caveats. While slightly verbose, every sentence provides useful information and there is no filler. It earns its length for a composite tool with multiple external dependencies.

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?

With no output schema, the description fully enumerates the return structure (summary block fields, per-advisory details, links, alternative versions) and explains error/partial-failure behavior. For a complex tool with two external data sources and potential timeouts, this is complete and self-contained.

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 description coverage is 100% (both package and version are described). The description adds no new parameter details beyond the schema; the schema already covers scoped packages and default version. Baseline 3 is appropriate since the schema does the heavy lifting.

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 it is a composite 'should I add this npm package to my project' check, specifying the exact data sources (deps.dev and bundlephobia). It names specific outputs and distinguishes itself from sibling tools by being the dedicated npm dependency assessment tool.

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...' and provides concrete example queries. It also gives an exclusion: NPM only in v1, and directs other ecosystems to deps.dev:version directly. This fully guides when to use and when not to.

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