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

Annotations already provide readOnlyHint=true and openWorldHint=false, establishing that the tool is read-only and returns a complete set. The description adds behavioral context beyond annotations by stating it returns 'expiry times' and excludes 'permanent sites,' which are not captured in the structured metadata. This adds value without contradiction, though it could mention ordering or limits for full transparency.

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 a concise two-sentence structure, front-loaded with the key action and scope ('COMPLETE list...'), followed by an exclusion and an alternative pointer. Every sentence earns its place with no redundancy or fluff.

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?

Given no parameters, no output schema, and annotations covering read-only and closed-world behavior, the description fully specifies what the tool returns (temporary previews with expiry times), what it excludes (permanent sites), and when to use an alternative. An agent has all necessary information to invoke the tool correctly.

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?

The tool has zero parameters and an empty schema, so schema coverage is effectively 100% (trivially). The description does not need to explain parameters, and the baseline for 0 params is 4. No additional parameter semantics are required.

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 a specific verb ('list') and resource ('temporary previews on this Nippy account'), and explicitly differentiates from the sibling tool list_sites by noting it provides a combined overview. It also specifies what is excluded (permanent sites), leaving no ambiguity about the tool's scope.

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 explicitly tells the agent when to use this tool versus an alternative: 'For a combined overview of sites and previews, use list_sites.' This is a direct and clear usage guideline, and the exclusion of permanent sites further clarifies the intended context.

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