list_circle_members

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

Annotations only declare readOnlyHint=true, but the description adds real behavioral context: the returned fields (has_telegram/has_whatsapp booleans, enrolled_phone_hint) and the security guarantee that a full identifier is NEVER returned. Auth requirements are also disclosed. It could still say more about pagination or empty-circle behavior.

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?

Front-loads the purpose, then a short return-shape sentence, then a clearly labeled ACCESS block. Two compact paragraphs, all of it functional. The access note is slightly verbose but earns its place by preventing a predictable failure.

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?

With no output schema, the description supplies the return shape and the security constraint on returned fields, plus the auth prerequisite. An agent has everything needed to decide to call it and to interpret the response correctly.

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% (the single 'id' parameter is documented as 'Circle ID' with a 24-hex pattern), so the schema already does the work. The description adds no syntax or format detail beyond that, which is the expected baseline.

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?

States a specific verb+resource ('List a Circle's members'), which clearly separates it from list_circles and get_circle in the sibling set. It also reinforces purpose by describing what each returned member carries. It does not explicitly name the alternatives it is not, so it falls just short of a 5.

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?

Gives a clear prerequisite and routing rule: it needs a Proof account, PROOF_API_KEY must be set, and importantly 'start_login does NOT open this tool' — a non-obvious negative that prevents a failed call. It stops short of explicit when-to-use guidance vs list_circles/list_circle_member_channels.

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