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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, so the safety profile is fully covered. The description adds the deprecation flag and the cross-registry scope, but the field list largely duplicates what the output schema would document. With rich annotations and an output schema, the incremental behavioral disclosure is modest.

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 tightly written sentences: the payload is front-loaded, the ecology scope closes it out, and there is no redundant or filler text. Every clause carries information an agent needs to call the tool.

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?

For a two-parameter read-only lookup with full schema coverage, rich annotations, and an output schema, this is essentially complete; the description needn't explain return values. The only omission is guidance pointing to sibling tools when the agent needs health, downloads, or dependency data instead.

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 both parameters are already documented, and the enum constrains ecosystem. The description only restates the ecosystem list ('npm, pypi, cargo') and adds no format guidance for 'name' (e.g., scoped packages, case sensitivity). Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific verb and resource ('Get core metadata for a package') and enumerates the exact fields returned (version, description, license, homepage, repo, maintainers, deprecated flag), which implicitly separates it from siblings like package_downloads or package_dependencies. However, no sibling is named explicitly, so the agent must infer the boundary against package_health and package_versions.

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?

'Use before an agent installs or recommends a dependency' gives a clear, actionable trigger condition for when this tool applies. There are no exclusions or named alternatives (e.g., when to prefer package_health or package_versions), so the routing guidance stops short of the explicit when-not framing.

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