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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds valuable behavior: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, and sources_failed list will contain timed-out sources. This goes beyond the 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 relatively long but well-organized: it starts with the core purpose, then lists use cases, return contents, limitations, and edge cases. Every sentence adds value, though it could be slightly more concise.

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, the description thoroughly explains the return format: summary block (with specific fields), per-advisory detail, links, and alternative versions. It covers NPM-only scope, partial failure behavior, and timing. Very complete for a complex composite tool.

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. The description adds that scoped packages (e.g., @types/node) are accepted, and version defaults to latest when omitted. This adds useful 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 uses a specific verb+resource ('scan_dependency') and clearly states it is a composite check for 'should I add this npm package', covering license, advisories, version history, bundle size, etc. It distinguishes itself from sibling tools by being a one-call composite for npm packages.

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: 'Use whenever an agent asks is X safe / popular / small or what does adding lodash cost me'. It also notes the NPM ecosystem limitation in v1 and mentions partial failure behavior. No explicit exclusions for other use cases, but context is clear.

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