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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds what the response contains (description, licenses, links, latest version, download counts), which is useful, but says nothing about rate limits, auth, or error behavior for a missing package.

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 short sentences, zero filler, with the core action and the resource front-loaded before the return-value list. 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 one-parameter, read-only lookup with no output schema, the description covers the action, the domain (Elixir/Erlang mix packages), and the return fields an agent would care about. Only the behavior on an unknown package name is left unstated.

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 100% and the single `name` parameter already carries an example-bearing description, so the schema does the heavy lifting. The description's "by name" adds only the framing that the lookup is keyed on the package identifier, nothing beyond that.

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?

"Look up a single Hex.pm package (Elixir/Erlang mix package) by name" states a specific verb, resource, and scope, and the word "single" implicitly separates it from search/list siblings. It stops short of naming those siblings explicitly, so it is clear but not fully differentiated.

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 rather than stated: an agent can infer this is the right tool when it already knows a package name, as opposed to searching. There is no explicit when-to-use vs. hex_pm_search_packages, hex_pm_get_release, or hex_pm_list_releases guidance, and no prerequisites mentioned.

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