Verify an npm package name before installing

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

With no annotations, the description carries full disclosure burden. It transparently explains the output: 'Returns a verdict (SAFE / CAUTION / SUSPICIOUS / DOES_NOT_EXIST) with the reasons' and lists the criteria (existence, age, downloads, deprecation, edit-distance). It also communicates the safety rationale. It does not mention whether the tool makes network calls or has side effects, but for a verification tool this is not a significant gap.

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 three sentences that flow logically: purpose, when to use, and output/behavior. It is front-loaded with the core function, and every sentence provides meaningful information without fluff. The structure is easy to parse and complete.

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 low complexity (one parameter, no output schema), the description is highly complete. It explains the return values and the reasons, which substitutes for an output schema. It also addresses the risk context. However, it could be slightly richer by clarifying how to act on CAUTION or SUSPICIOUS verdicts, but this is not critical.

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?

The input schema already describes the 'name' parameter with high coverage (100%). The description reinforces its meaning by saying 'the exact npm package name you intend to install' and ties it to the safety check, but it doesn't add new syntactic details beyond the schema. Therefore, a baseline score of 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's purpose: 'Check that an npm package name is REAL and safe' and mentions it returns a verdict. It is specific about the resource (npm package name) and the action (checking). However, it does not explicitly differentiate from the sibling tool 'verify_packages' (plural), which may handle multiple packages, so it doesn't fully distinguish between them.

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?

The description provides explicit when-to-use guidance: 'Reach for this whenever you are about to add a dependency you are not 100% certain exists' and warns against hallucinated package names. It also gives a clear exclusion-like rule: 'If it doesn't exist, do not install it.' However, it does not mention alternatives or explicitly say when not to use this tool (e.g., when verifying multiple packages, use the sibling).

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