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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description adds real context beyond them: the admin-scope requirement and the reason for it, plus the enumerated role values (viewer, member) and status values (active, invited, expired). It does not mention return shape beyond those fields or any pagination, which keeps it from a 5.

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 returned content leads and the auth constraint follows. Every clause carries information an agent would not get from the structured fields alone.

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 simple one-parameter read tool with no output schema, the description supplies the missing piece that matters — the contents of the response and the permission required to get it. Parameter behavior is fully covered by the schema, so nothing essential is absent.

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?

There is a single 'site' parameter at 100% schema description coverage, including the domain/id/public-id forms and the optionality rule, so the schema already does the work. The description only refers to 'the site' generically and adds no syntax or selection guidance, which is the baseline 3 case.

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 names the resource (the owner and invited people of a site) and the fields returned (role, status), which makes it clearly distinct from siblings like list_sites or list_api_keys. The verb 'list' comes only from the title, so the description itself is a noun phrase, but the intent is unambiguous.

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 states a hard prerequisite — admin scope is required because email addresses are returned — which is genuine usage guidance. However, it gives no when-to-use framing and never contrasts with adjacent tools such as invite_team_member, update_team_member, or remove_team_member, leaving the agent to infer that this is the read path.

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