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

Annotations declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint=false. Description adds valuable context: composite nature fans out across two services, partial failures degrade gracefully, bundlephobia first measurement can take 5-30s, sources_failed will list failures. No contradictions.

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 a single paragraph but well-organized, front-loading purpose and usage, then covering composite behavior, return format, ecosystem scope, and failure handling. Every sentence adds value, though could benefit from more structuring (e.g., bullet points).

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 the tool's complexity (composite, multiple services, partial failures, timing), the description covers all important aspects: return format details (summary block, per-advisory detail, links, alternative versions) and failure behavior. No output schema, but description adequately explains what is returned.

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% with good descriptions for both parameters. The description adds context about default version behavior and scoped package acceptance, but the schema already provides adequate documentation. 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 states the tool performs a composite check for evaluating npm packages, combining deps.dev and bundlephobia data. It uses specific verbs ('scan', 'fans out') and distinguishes from siblings 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 says 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also notes NPM ecosystem only in v1, and describes partial failure behavior. Provides clear when-to-use and ecosystem constraints.

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