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

Description adds valuable behavioral context beyond annotations: partial failures degrade gracefully, bundlephobia may take 5-30s on first measurement, and sources_failed will list timeouts. Annotations already indicate readOnly, openWorld, idempotent, and non-destructive.

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?

Description is front-loaded with purpose and efficient, but slightly long (4 sentences). All sentences provide necessary information; no waste.

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 complexity (multi-source, no output schema), description covers scope, fallbacks, example prompts, and lists output fields. However, output format details are inferred; some agents might need more explicit structure.

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%, so baseline is 3. Description adds minimal extra info beyond schema (e.g., version defaults to latest). No additional constraints or formats explained.

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 explicitly states the tool is a composite check for evaluating npm packages, combining multiple data sources (deps.dev and bundlephobia). Clearly distinguishes from siblings by specifying scope (NPM only 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 usage triggers: 'whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me". Also mentions limitations and alternatives for other ecosystems.

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