add_list_member

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

No annotations are provided, so the description carries the full burden. It only describes the basic operation and parameter requirement. It does not disclose side effects, authentication needs, rate limits, error behavior (e.g., if user already a member), or idempotency.

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 very short, with two paragraphs. The main action is front-loaded. Every sentence provides essential information without redundancy.

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 add operation with an output schema present, the description covers the core purpose, input constraint, and parameter details. It lacks behavioral context (e.g., success confirmation, error cases), but given the tool's simplicity and the presence of an output schema, it is fairly complete.

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 has 0% description coverage, so the description adds significant value by explaining each parameter's format (e.g., 'without @' for screen_name, 'numeric' for user_id) and the requirement that one of the two must be provided. This goes beyond the schema's titles and types.

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 clearly states 'Add a user to a Twitter List', which uses a specific verb and resource. It distinguishes from sibling tools like 'remove_list_member' by its action.

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 specifies the constraint that exactly one of screen_name/user_id must be provided. However, it does not explicitly guide when to use this tool versus alternatives like remove_list_member, nor does it mention prerequisites (e.g., list ownership).

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