add_member

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

No annotations are provided, so the description must disclose side effects and behavior. It only states what the tool does, not how it behaves in edge cases (e.g., duplicate email, status semantics, whether an opt-in confirmation is sent for 'pending'). The description is too sparse to convey behavioral transparency for a mutation 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 a single, clean sentence that immediately states the purpose. It wastes no words. However, given the tool's parameter complexity and lack of annotations, a second sentence on usage or behavior would make it more appropriately sized, so it is not a perfect 5.

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?

The tool has 5 parameters, an enum, nested objects, and no output schema or annotations. The description is minimal and does not explain expected returns, error scenarios, or behavior when a member already exists. It is not complete enough given the tool's complexity.

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 input schema provides descriptions for all 5 parameters (100% coverage), including examples like merge_fields. The tool description adds no additional parameter meaning beyond what the schema already states. Per the rubric, this is a baseline 3 — the schema carries the burden.

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 'Add a new subscriber to an audience' clearly identifies the action (add) and the resource (new subscriber to an audience). It distinguishes from update/archive/delete operations by using 'new', but does not explicitly mention alternatives like tag_member or update_member, so it slightly lacks sibling differentiation.

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?

No guidance on when to use this tool versus alternatives. It does not mention prerequisites (e.g., the audience must exist) or clarify that for existing members one should use update_member. The description offers no context for choosing add_member over tag_member or other available operations.

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