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

Annotations already disclose that this is a non-destructive mutation (readOnlyHint=false, destructiveHint=false) and that it is not idempotent. The description adds that settings are optional, which is useful, but it does not mention permissions, duplicate-name behavior, or what the call returns. The description adds some value but not rich behavioral context beyond annotations.

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?

A single, front-loaded sentence that states the action, the resource, the domain of use, and the optional settings. There is no redundant or filler text.

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?

Given seven parameters with nested objects, no output schema, and a create mutation, the description is somewhat thin. It does not address duplicate audience names, required verified-domain constraints for confirmation emails, or what the call returns. The schema and annotations compensate partially, making it adequate but with clear gaps.

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 71%, so the schema already carries most parameter meaning, including visibility, public_name, double_opt_in, and confirmation_email. The phrase 'optionally with its settings' correctly signals that only the name is required and the remaining seven parameters are optional settings, but it does not explain the individual settings beyond what the schema already documents.

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 ('Create an audience') and clarifies the resource as a mailing list, which distinguishes it from update-audience, delete-audience, and list-audiences. The added purpose ('for campaigns and automations') makes the tool's role immediately clear.

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 usage by saying the audience is 'for campaigns and automations', but it does not state when to use this tool versus update-audience or merge-audiences, nor does it mention any prerequisites such as unique naming. It gives context but no explicit exclusions or alternatives.

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