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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real value beyond that by disclosing the return content (members with roles, pending invites with ids) and an authorization constraint (owner-only) that annotations do not express.

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 sentences, no filler: the resource and contents come first, the access constraint is front-loaded at the end. Every clause carries information an agent needs.

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 tool with no output schema, the description covers what is returned and who may call it. The only gap is what happens when the optional id is omitted (does it default to the selected site?), which list_sites/select_site siblings imply but do not confirm.

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 single id parameter is fully documented in the schema as 'Site id.' and the description adds no further semantics such as format, defaults, or behavior when id is omitted (it is listed as not required). With 100% schema coverage, the baseline 3 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?

Specific verb+resource ('List a site's members') plus the extra payload detail that pending invites and their ids are included. It does not, however, distinguish itself from the sibling list_members, leaving the agent to infer that one is site-scoped and the other presumably workspace-scoped.

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?

'Owner-only.' gives a useful precondition for calling, but there is no explicit statement of when to prefer this over list_members or list_membership_plans, which are the obvious alternatives in a crowded list/member tool family.

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