add_contacts_to_list

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

With no annotations present, the description carries full responsibility for behavioral disclosure. It marks the tool as a '[mutation]', which is helpful, but fails to explain side effects (e.g., what happens if list_id is invalid, duplicate contacts behavior, permission requirements). The example 'update_drive' with similar minimal transparency received a 2, which is consistent here.

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 extremely concise, using two short sentences. It front-loads the purpose and includes the mutation marker without any fluff. Every word earns its place, adhering to the principle of minimal necessary information.

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 tool with two parameters and no output schema, the description covers the basic purpose. However, it lacks contextual details such as error handling, prerequisites (e.g., existence of list), and potential side effects. Given the lack of annotations, it could be more comprehensive to guide an agent effectively.

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%, and the schema already describes both parameters ('list_id' and 'contacts') with clear details. The description adds only that contacts are 'one or more' and that it's a marketing list, which does not significantly enhance understanding beyond the schema. Baseline 3 is appropriate.

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 the action 'Add contacts to list' and elaborates with 'Añade uno o más contactos a una lista de marketing', specifying the resource (marketing list) and the operation (adding contacts). This distinguishes it from sibling tools like 'remove_contact_from_list' or 'create_contact_list'.

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 is provided on when to use this tool versus alternatives (e.g., 'import_contacts_csv', 'bulk_add_to_blacklist'), nor are prerequisites or exclusion conditions mentioned. The agent is left to infer usage solely from the tool's name and short description.

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