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

The annotations already declare readOnlyHint=true, so no further safety disclosure is needed. The description adds useful context about completeness ('COMPLETE list') and the 'no expiry' distinction, but does not add rich behavioral details beyond that. This is comparable to a straightforward read-only list tool with reasonable but minimal added context.

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 tight sentences with no filler. The most important fact ('COMPLETE list of permanent sites') is front-loaded, and the preview exclusion and alternative tool are stated efficiently.

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 no-parameter, read-only list tool with no output schema, the description is complete: it identifies what is returned, what is excluded, and which sibling to use for the broader view. No critical information is missing.

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, so the schema fully documents everything an agent needs. The description reinforces the scope and content of the result, but there is no parameter ambiguity to resolve. Baseline 4 is appropriate for a no-parameter tool.

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') and a precise resource ('permanent sites on this Nippy account'), and clarifies that it excludes previews. This clearly distinguishes it from list_sites and list_previews without needing to inspect schemas.

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?

It explicitly says previews are not included and directs the agent to list_sites for a combined overview of sites and previews. This gives a clear selection rule and names the relevant alternative tool.

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