list_circle_members

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

Goes beyond readOnlyHint=true by disclosing the returned fields (has_telegram, has_whatsapp, enrolled_phone_hint), the masking rule, and the policy reference SEC-PM-006 that a full identifier is never returned. It also surfaces the authentication prerequisite, which is behavioral context an agent cannot get from annotations. It stops short of describing ordering, pagination, or failure modes.

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 tight blocks: what is returned first, then the access gate. Every sentence carries information — the masked-phone example clarifies the format without a diagram, and the SEC-PM-006 reference is compact provenance rather than filler.

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?

An output schema exists, so the description was not obliged to enumerate return fields, yet it helpfully flags the privacy guarantee that the schema alone would not convey. For a one-parameter, read-only list tool, the only real gap is the absence of any statement about result size or ordering.

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 has 100% schema description coverage ("Circle ID" with a 24-hex pattern), so the schema already carries the semantics. The description adds no format, sourcing, or lookup guidance for obtaining the Circle ID, so it earns only the 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 and resource ("List a Circle's members") and immediately characterizes what each member record contains. It does not explicitly distinguish itself from siblings such as get_circle or list_circle_member_channels, so an agent must infer the boundary rather than being told.

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?

There is no explicit when-to-use versus alternative guidance relative to get_circle or list_circles. The access block does supply a genuine exclusion — that start_login will not unlock this tool and PROOF_API_KEY plus a restart is required — which is useful routing information, but it addresses authentication, not tool selection.

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