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

The annotations already provide readOnlyHint, destructiveHint, idempotentHint, and openWorldHint. The description adds behavioral context: it returns the latest version by default and supports scoped packages. This adds value beyond annotations without contradicting them.

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 two concise sentences, front-loading the core functionality. Every sentence provides essential information without fluff.

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 output schema exists and annotations cover safety, the description adequately covers what the tool returns and its version behavior. It omits error handling (e.g., missing package), but this is minor for a read-only info tool.

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 both parameters documented. The description reiterates the version defaulting behavior but does not add significant new meaning beyond the schema examples.

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 it retrieves metadata for an npm package and lists the specific fields returned. It also mentions support for scoped packages and version defaulting, making the tool's purpose unambiguous. The tool is well-distinguished from siblings like npm.packages.search or npm.packages.downloads.

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 implies usage for fetching metadata of a single package, but does not explicitly provide when to use vs alternatives (e.g., npm.packages.search for searching, npm.packages.versions for listing versions). No exclusion criteria or context for when not to use is given.

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