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

The description goes beyond the readOnlyHint/idempotentHint annotations by disclosing composite fan-out behavior, potential 5-30s latency on first bundlephobia measurement, and graceful degradation via sources_failed. It also explains partial failure behavior, which is valuable operational context not visible in structured data.

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 and well-structured: it starts with the primary purpose, then gives use cases, output summary, ecosystem scope, and failure behavior. Every sentence contributes valuable detail without redundancy, appropriate for the tool's composite nature.

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 compensates by enumerating the exact return fields, including per-advisory details, links, recent versions, and sources_failed. It also addresses timing expectations and edge cases (new version measurements), making the tool's behavior fully transparent.

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%, so parameters are fully described in the schema. The description adds context about the npm-specific meaning of 'package' and version defaulting, but this mostly mirrors the schema. No additional parameter semantics beyond what the schema already provides.

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 states a specific verb ('scan') and resource ('dependency') with a clear composite purpose: determining whether to add an npm package to a project. It clearly distinguishes from siblings by specifying it covers license, advisories, version history, and bundle metrics, and explicitly notes the npm-only scope in v1.

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 provides when-to-use guidance: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also names the alternative for non-npm ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'), giving clear exclusions.

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