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

Annotations already cover the read-only, idempotent, non-destructive safety profile. The description adds the useful fact that each release comes with its version and publish date, which partially substitutes for the missing output schema. It does not disclose pagination, ordering, or any API limits, but the bar is lower given the strong 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?

A single, front-loaded sentence that states the action, resource, and return details with no filler. Every clause earns its place.

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 simple one-parameter, read-only list tool, the description is complete: it names the package, the fact that all published versions are returned, and the key fields included. The robust annotations cover safety, and no output schema means the return description is especially valuable.

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 the 'name' parameter is already fully documented. The description adds that the package is a Hex.pm/Elixir/Erlang mix package, which gives useful context but does not materially expand on the schema's definition.

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 ('List'), a clear resource ('published versions (releases) of a Hex.pm package'), and the exact fields returned. It is clear and precise, though it does not explicitly differentiate itself from siblings like get_release or search_packages.

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?

There is no guidance on when to choose this tool over alternatives, no exclusions, and no mention of related tools. The purpose is implied, but the description does not help an agent route between list_releases, get_release, or search_packages.

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