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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds that only published releases are returned and that each entry carries version and publish date, which is real value. It stops short of noting ordering, pagination, or behavior for unknown/private packages.

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?

One sentence, front-loaded with the verb and resource, with the parenthetical domain qualifier placed where it aids rather than interrupts. Nothing extraneous.

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 one-parameter read tool with no output schema, the description supplies the essential return shape (version + publish date) and the published-only scope. Ordering and empty-result behavior are unstated, a minor gap for such a simple 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?

There is a single required parameter with 100% schema coverage, so the schema already documents it fully. The description's only added meaning is the domain framing (Hex.pm / Elixir-Erlang mix package), which is marginal but non-zero.

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 names a specific verb (List) and resource (all published versions/releases of a Hex.pm package), and disambiguates the ecosystem as Elixir/Erlang mix packages. It implicitly contrasts with get_package/get_release by emphasizing enumeration of all versions, though it does not name those siblings explicitly.

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?

Usage is implied: call this when you need the version history of a known package name. There is no explicit statement of when to prefer this over hex_pm_get_package or hex_pm_get_release, and no prerequisites or exclusions are given.

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