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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses composite behavior, fan-out to two services, graceful degradation on partial failures, timing (5-30s for bundlephobia), and the sources_failed field. This goes well beyond the structured 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 packed with essential information, front-loaded with the core purpose. Though multi-sentence, every sentence adds value: sources of data, use cases, return fields, ecosystem scope, and degradation behavior. No redundant content.

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 explains the return value structure (summary block fields, per-advisory detail, links, alternative versions). It also covers failure modes and ecosystem limitations, making it self-contained 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?

Schema coverage is 100% with clear descriptions for 'package' and 'version'. The tool description does not add additional parameter-specific detail, but the schema already carries the meaning. 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 clearly states a specific verb+resource: scanning an npm package dependency for a 'should I add this' check. It distinguishes from siblings by explicitly scoping to npm in v1 and directing other ecosystems to deps.dev:version.

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?

Provides explicit when-to-use guidance ('Use whenever an agent asks...') and exclusion criteria (other ecosystems go to deps.dev:version). This is stronger than most alternatives.

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