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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, eliminating ambiguity about side effects. The description adds valuable behavior beyond that: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30 seconds, and the sources_failed field will list timeouts. No contradiction with 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?

While long, the description is densely informative and every sentence serves a purpose: purpose, usage trigger, output summary, ecosystem scope, and failure behavior. The front-loaded sentence immediately conveys the core function. No redundant 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?

With no output schema present, the description thoroughly explains the return value structure (summary block fields, per-advisory detail, links, alternative versions). It also covers latency, failure handling, and ecosystem scope. For a composite tool with external APIs, this makes the tool fully self-contained for an agent.

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 parameters are fully documented in the schema (package name, version). The description adds context about the tool's npm-only dependency and that version defaults to latest, but this is already stated in the schema. It doesn't introduce new parameter semantics, so the baseline 3 applies.

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 opens with a specific and vivid purpose: a composite check for adding an npm package to a project, fanning out across deps.dev and bundlephobia. It clearly distinguishes this tool from siblings (e.g., scan_competitor_ai_presence) by explicitly limiting scope to the NPM ecosystem and focusing on package health/size metrics.

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 is provided: 'Use whenever an agent asks "is X safe / popular / small" or "what does adding lodash cost me"'. It also states an exclusion/alternative: for PyPI/Maven/Cargo/Go, one should use deps.dev:version directly. This makes when-to-use and when-not-to-use clear.

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