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

Annotations already declare readOnlyHint and openWorldHint, and the description adds valuable context beyond those: the honest 'not found' behavior, the network-fetch nature, and the specific data points consulted. 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?

Three dense sentences front-load the purpose and scope, with each clause adding useful information. The final 'Read-only, open world (network fetch)' partially repeats the annotations, but it also adds the network detail, making it acceptable rather than wasteful.

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 enumerates the key output dimensions (existence, latest version, publish date, description, license, maintainers, owner) and the not-found behavior, effectively compensating for the absence of an output schema. For a simple one-parameter tool, this fully equips an agent to invoke 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?

The input schema already documents the only parameter with 100% coverage, including an example and lowercase requirement. The description adds no additional parameter-specific syntax or formatting details, so the baseline of 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 starts with a specific verb, 'Verify', names the exact resource ('npm package' against registry.npmjs.org), and enumerates the concrete checks performed. This clearly distinguishes it from sibling tools like verify_repo and verify_claim, which target different artifact types.

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 instructs when to use it: to ground claims like 'he published an npm package' in registry data instead of the portfolio's. It provides clear context but does not explicitly name an alternative sibling tool or state when not to use it, so it stops short of the highest tier.

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