add_users_to_audience

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

With no annotations, the description partially carries the transparency burden by specifying that the payload must be hashed and formatted as a JSON string with a schema. However, it does not disclose side effects, prerequisites (e.g., audience must exist), idempotency, or error behavior, leaving significant gaps for a mutating tool.

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?

The description is two sentences, with the primary action front-loaded and the payload constraint stated in a single additional sentence. There is no filler or redundancy, making it maximally efficient for its length.

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 2-parameter mutation tool, the description covers the core action and essential payload format, but omits details like response behavior, whether the audience must pre-exist, and handling of duplicate users. Given no annotations or output schema, a slightly richer description would be expected for full completeness.

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 coverage is 100%, so both parameters are documented. The description adds a concrete example of schema values (EMAIL, PHONE, FN, LN) that supports but mostly repeats the schema's payload description. It does not introduce new semantic meaning beyond highlighting the hashing requirement, which is already in the schema.

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 ('Add') and names both the resource ('users') and target ('custom audience'), making the tool's function immediately obvious. It also distinguishes this from sibling tools like remove_users_from_audience and create_custom_audience by showing it adds to an existing audience.

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 (adding users to an audience) but provides no explicit guidance on when to use this tool versus alternatives, such as create_custom_audience or update_audience. There are no stated exclusions or conditions, so the usage context is only implied by the tool name and action.

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