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

The annotations already declare readOnlyHint=true, so the description's job is to add value beyond that. It does so by explaining that membership is computed and can change without editing the audience, which is a meaningful behavioral trait. It also implicitly confirms it's a read operation consistent with the annotation. It doesn't cover pagination or return format, but for a read-only list tool, this is a solid contribution.

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 with no filler. The first sentence states the core purpose, and the second adds a key behavioral nuance. The information is front-loaded and every word earns its place. It avoids repeating schema details or annotations.

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 list tool with two parameters, a readOnly annotation, and no output schema, the description captures the essential nuance (dynamic membership). It doesn't mention pagination explicitly, but the cursor parameter is described thoroughly in the schema, so the agent can infer. It's complete enough for correct invocation without being verbose.

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 schema has 100% coverage for both parameters (audience_id and cursor) with clear descriptions. The tool description adds no additional meaning beyond what the schema provides. Per the calibration, baseline 3 applies when schema fully documents parameters, and the description doesn't compensate for anything missing.

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 states a specific verb ('List'), a clear resource ('users who currently match an audience's filter'), and distinguishes it from similar tools like list_audiences (lists audiences) and get_audience (gets an audience). The nuance that membership is computed and reflects current profiles adds specificity beyond a generic 'list members' phrasing, making it easy for an agent to identify the exact purpose.

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 implies when to use it (when you need the current members of an audience) but provides no explicit exclusions or alternatives. It doesn't mention that for static lists, get_list_subscribers might be more appropriate, or that it's read-only. The behavioral note about computed membership gives context but not direct guidance on choosing this over siblings.

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