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

Annotations already cover idempotency and non-destructiveness; the description adds the live-registry source, version-selection behavior, the $0.01 x402 payment expectation, and the optional operation id for retry compatibility. The readOnlyHint=false annotation is not contradicted because the paid x402 flow implies a financial side effect, which the description discloses.

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?

Two sentences with no filler: the first sentence delivers purpose and differentiation, and the second covers the key payment/operation-id detail. The most decision-relevant information is 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?

The description explains the core purpose, pricing, and version behavior, but with no output schema it does not enumerate what 'facts' are returned (e.g., license, maintainers, dist-tags). The x402 challenge/retry flow is left to the schema parameter descriptions rather than the tool summary, leaving minor gaps for an agent invoking a paid 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 coverage is 60%, and the three salt/x402 parameters already have their own schema descriptions. The tool description adds the missing semantic context for package and version by clarifying that the version is optional and that 'latest or requested' version is returned, which is important behavior not present in the raw 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 states a specific verb and resource: 'Return live npm registry facts' for the 'latest or requested package version.' It also differentiates itself from the higher-priced vulnerability/adoption layer, which aligns with the sibling npm-package-intel tool, so an agent can identify what this tool is and is not.

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 phrase 'without the higher-priced vulnerability and adoption decision layer' gives clear context for when this tool is appropriate: when basic registry facts are needed, not vulnerability or adoption analysis. It does not explicitly name sibling alternatives or provide a when-not-to-use list, but the contrasting language is sufficient direction.

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