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

With no annotations provided, the description carries the disclosure burden and does well: it reveals the surprising behavior that an identifier is NEVER returned and that only has_telegram/has_whatsapp booleans are provided. It also flags the access requirement. It could go slightly further with return shape or error behavior, but the key behavioral quirks are disclosed.

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 compact and front-loaded: the core purpose appears first, followed by the return-data constraint, then the access instructions. Every sentence adds necessary information; there is no filler or repetition.

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 list operation with no output schema, the description covers the essential context: what is returned, what is not returned, and how to authenticate before invoking. It could be slightly more explicit about pagination or the shape of the returned list, but nothing critical is missing for correct invocation.

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?

Schema description coverage is 100%, and the schema already names the parameter, describes it as 'Circle ID', and enforces a 24-hex pattern. The description adds no new parameter-level meaning beyond referring to 'a Circle', so the baseline of 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?

The description opens with a specific verb and resource: 'List a Circle's members.' It also states exactly what data each member carries (presence booleans only), which distinguishes it from related tools like list_circle_member_channels or remove_circle_member.

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 gives clear context: a Proof account is required, the client must be authenticated, and start_login does NOT open this tool. It does not explicitly name an alternative for when to use it, but for this tool the main usage blocker is the auth prerequisite, which is addressed directly.

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