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

With no annotations provided, the description carries the full behavioral burden. It usefully states that the operation is read-only and free, but does not disclose return format, pagination, ordering, or authentication requirements, leaving meaningful gaps for a list operation.

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 tightly written sentences front-load the core purpose and audience distinction. Every phrase adds useful routing or behavioral information, with no repetition or 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?

For a zero-parameter list tool with no output schema, the description sufficiently explains what is listed, how it differs from `list_custom_audiences`, and that the call is read-only and free. It could still be richer about returned fields, but the essential selection information is present.

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 tool has zero parameters, so there are no parameter semantics to explain. The schema is empty and the description appropriately avoids inventing or describing nonexistent inputs.

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 uses a specific verb (List) and resource (CAMPAIGN audiences), adds scoping detail (filter-based, attachable to campaigns), and explicitly distinguishes this from the custom-audience listing tool. An agent can identify this tool without opening its schema.

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?

It clearly routes the agent to `list_custom_audiences` for uploaded, purchased, or CRM-built lists, which defines the primary alternative. However, it does not state any other conditions for choosing this tool or mention edge cases where neither audience type applies.

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