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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, destructiveHint=false. The description adds valuable context: it's a composite fan-out to two services, partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed lists timed-out services. This goes beyond 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 moderately long but front-loaded with core purpose. Every sentence adds value: explains composite nature, usage guidance, caveats about timing and partial failures, and return fields. Could be slightly tighter but still well-structured.

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 no output schema and 2 parameters, the description is quite complete. It covers composite behavior, services used, summary fields, failure modes, and ecosystem scope. Return structure is described at a high level but sufficient.

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 descriptions for both parameters. Description adds that package names can be scoped (e.g., @types/node) and version defaults to latest. This provides additional nuance beyond the schema.

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 the tool performs a composite check for npm packages across deps.dev and bundlephobia, answering whether to add a package. It uses the specific verb 'scan' and resource 'dependency', and distinguishes from siblings by mentioning ecosystem limits and fallback tools 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: 'whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. Also specifies when not to use: 'PyPI / Maven / Cargo / Go fall under deps.dev:version directly', providing clear alternatives.

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