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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior, so safety is covered. The description adds the only return-shape information available (there is no output schema) by naming the five exposed fields, plus the cross-tool contract that ids/domains flow into other tools. It does not say whether the list is paginated or how many sites typically return.

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 with no filler; the payload (what you get back) is front-loaded and the downstream id/domain contract follows immediately. 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 zero-param, read-only discovery tool this covers purpose, returned fields, and how the results feed sibling tools. The only meaningful gap is the absence of any note on result size or pagination, which matters if a user belongs to many sites.

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 takes zero parameters and additionalProperties is false, so there is nothing for the description to disambiguate. Baseline of 4 applies.

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 the resource ('the websites you can open in SuprAnalytics') and the exact fields returned (id, name, domain, timezone, currency), so an agent knows precisely what it gets. The verb 'list' comes from the name rather than the prose, and no sibling is named, but the resource is distinct from list_funnels/list_goals/list_segments.

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?

'Other tools take a website id or domain' implicitly signals this is the discovery step before calling analytics tools, which is useful routing context. However, it never explicitly says 'call this first when you lack a website id', and offers no when-not guidance or comparison against get_websites_summary.

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