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

Description discloses that the tool fans out across two external services, that bundlephobia's first measurement can take 5-30s, and that partial failures degrade gracefully with a sources_failed list. This adds context beyond the annotations (readOnly, idempotent) about potential latency and error handling.

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 well-organized: purpose first, then usage, then output details, then edge cases. Every sentence adds value, though it could be slightly more concise. Still, no filler.

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 return structure (summary block, per-advisory detail, links, recent versions) and handles partial failures. The tool complexity is high (composite, external services), and the description covers all necessary context.

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% (both parameters described). The description adds context that package is an npm package name (scoped accepted) and that version defaults to latest, which is already in schema. However, it also explains how parameters are used in the composite check, slightly improving 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 states the tool's composite nature: checking npm package safety and size via deps.dev and bundlephobia in one call. It distinguishes itself from siblings by specifying the npm ecosystem and the exact data sources, making the purpose unambiguous.

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?

Explicit usage guidance: 'Use whenever an agent asks ...' and explains the scope (NPM only, other ecosystems via deps.dev). Also notes partial failures and timing for bundlephobia first measurement, helping the agent decide when to call this tool vs. alternatives.

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