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

Beyond the annotations (readOnly, idempotent, etc.), the description discloses critical behavioral traits: partial failure handling ('sources_failed will list it if it times out'), latency caveats ('first measurement can take 5-30s'), and the exact structure of the returned summary block. This goes well beyond the annotation baseline and fully informs the agent.

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 every sentence earns its place: purpose, usage, return details, ecosystem scope, and failure behavior. It is somewhat long but appropriately so for a composite tool; could be slightly more streamlined but remains well-structured and front-loaded.

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 values (summary fields, per-advisory detail, links, alternative versions). It also covers failure modes, performance expectations, and ecosystem limitations, making it fully complete for an agent to invoke and interpret results correctly.

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%, so the baseline is 3. The description adds only minor semantic nuance (e.g., 'NPM ecosystem only' clarifies the package parameter) but mostly the schema already carries the meaning. No significant enrichment beyond the structured fields.

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 begins with a specific verb+resource: 'Composite "should I add this npm package to my project" check in ONE call'. It clearly states the tool's function and distinguishes it from siblings by naming the fan-out sources (deps.dev and bundlephobia) and the NPM ecosystem focus.

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 guidance is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me".' It also names an alternative for non-NPM ecosystems ('PyPI / Maven / Cargo / Go fall under deps.dev:version directly'), making when-to-use vs alternatives crystal clear.

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