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

Beyond the readOnlyHint, openWorldHint, and idempotentHint annotations, the description discloses important behaviors: partial failures degrade gracefully, bundlephobia's first measurement can take 5-30s and will be listed in sources_failed if it times out, and the return structure includes summary block, per-advisory details, links, and alternative versions.

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 well-structured: a clear first sentence for purpose, followed by specifics. It is moderately long but every sentence adds value. Could be slightly more concise, but still effective for an agent.

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 (multiple data sources, partial failures) and the absence of an output schema, the description is remarkably complete. It covers the return fields, behavior on timeout, and ecosystem limitations, ensuring the agent can use it 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 schema already documents both parameters well. The description adds minimal extra meaning—it mentions scoped packages are accepted and that version defaults to latest, which is already in the schema. No additional semantics beyond the schema.

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 purpose as a composite check for adding an npm package, specifying the data sources (deps.dev, bundlephobia) and the aspects evaluated (license, advisories, version history, bundle size, etc.). It distinguishes itself from siblings by noting the NPM-only scope in v1.

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 when to use this tool: whenever an agent asks about safety, popularity, size, or cost of adding a package. Also clarifies ecosystem limitations (NPM only) and directs other ecosystems to a different tool (deps.dev:version).

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