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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, so the description does not need to restate safety. It adds valuable behavioral context by detailing the breadth of information returned, including every published version and its requires, autoload, and dist details, giving the agent a concrete expectation of the tool's output beyond the structured fields.

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?

The description is exactly two sentences. The first sentence front-loads the core purpose and input format with an example; the second enumerates the return fields in a compact list. Every word is functional, and there is no redundant or vague filler.

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 tool with a rich output schema and strong annotations, the description provides all necessary context: input format with example, output contents, and the questions it answers. It leaves no material gaps in understanding how to invoke or what to expect from the 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?

Schema coverage is 100% with the parameter 'name' described as 'Package name in "vendor/package" form'. The description repeats this format and adds an example, but does not introduce new semantic meaning beyond what the schema already provides. This matches the baseline for high schema coverage.

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 clearly states the tool retrieves the full Packagist registry record for a single PHP/Composer package in vendor/package format, with an explicit example (symfony/console). It enumerates the exact data returned (description, repository URL, maintainers, license, type, downloads, favers, and all published versions with requires/autoload/dist details), making its purpose distinct from sibling tools like list_versions or package_stats.

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?

The description gives clear context for when to use this tool: when you need a comprehensive registry record for one package and answers to questions about what the package is, who maintains it, and what each release declares. It does not explicitly name alternatives or state when not to use it, but the context is unambiguous and sufficient for an agent to choose it over more targeted tools.

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