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

Annotations already mark read-only, idempotent, open-world. Description adds valuable behavioral context: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s, sources_failed will list timeouts, and the tool fans out to multiple APIs. This goes beyond the structured annotations and informs the agent about non-obvious timing and failure behavior.

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 dense but well-organized: core purpose first, then usage triggers, then output summary, then limitations. Every sentence adds information; no filler. Length is justified by 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?

No output schema exists, so description must explain return fields and does so comprehensively, listing the summary block fields, per-advisory detail, links, and alternative versions. It also covers edge cases (timeout, partial failure). Given the tool's complexity, the description is complete and actionable.

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 description doesn't need to explain parameters. The description adds context about the overall purpose but not new parameter-level detail. The 'version' field's default behavior is already in the schema. Baseline 3 is appropriate.

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 identifies the tool as a composite check for npm package evaluation, specifying the exact question it answers ('should I add this npm package') and naming the two data sources (deps.dev and bundlephobia). It distinguishes this tool from siblings by focusing on a niche, multi-source scan rather than a generic search or entity lookup.

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 about safety, popularity, size, or cost of an npm package. Also provides an exclusion and alternative: 'NPM ecosystem only in v1; PyPI / Maven / Cargo / Go fall under deps.dev:version directly.' This tells the agent exactly when not to use this tool.

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