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

The description adds significant behavioral detail beyond the annotations, such as graceful degradation on partial failures, a 5-30s first-measurement timeout for bundlephobia, and the fact that sources_failed will list timeouts while the rest still returns. This supplements the readOnly/idempotent hints with operational nuance.

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 dense but every sentence carries unique value: purpose, usage, return fields, ecosystem constraint, and failure behavior. It is well-structured, front-loading the core purpose before details, and uses a practical example to illustrate usage.

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 adequately enumerates the return structure (summary block fields, per-advisory detail, links, alternative versions). It covers the tool's scope, limitations, performance characteristics, and error handling, fully equipping an agent to use it 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 descriptive entries for both package and version, so the description does not need to explain syntax or defaults. It adds minimal new parameter context beyond the schema, but the composite nature of the tool is hinted at, which slightly enriches understanding.

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 defines the tool as a composite npm package evaluation check, naming specific data sources (deps.dev, bundlephobia) and listing exact outputs. It distinguishes itself from other tools by specifying the NPM-only scope and the alternative approach for other ecosystems.

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 states when to use it: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' Also provides an alternative for other ecosystems: 'PyPI / Maven / Cargo / Go fall under deps.dev:version directly,' making the decision clear.

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