cm_add_subscriber

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

No annotations beyond title, so description must disclose behavioral traits. It mentions 'add or resubscribe' implying mutation, but fails to describe side effects, required permissions, or consequences of duplicate email addresses. The ConsentToTrack parameter and resubscribe behavior are hinted at via schema but not elaborated.

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?

Single sentence with no wasted words. Front-loaded with purpose. Efficiently communicates the core action.

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?

With 8 parameters, 3 required, and no output schema, the description is too sparse. It does not explain return values, behavior of key parameters like Resubscribe or CustomFields, or edge cases (e.g., what happens if subscriber already exists). A more detailed description is needed for this 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?

Schema coverage is 100%, so each parameter already has a description. The tool description adds minimal meaning beyond the schema; it repeats 'list' via 'to a list' but the schema already defines listId. Baseline 3 is appropriate as schema does the heavy lifting.

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 primary action: 'Add (or resubscribe) a subscriber to a list.' It uses a specific verb ('Add' and 'resubscribe') and identifies the resource ('subscriber to a list'), distinguishing it from sibling tools like cm_import_subscribers (bulk) and cm_update_subscriber (modifying existing).

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 such as cm_import_subscribers for bulk adding or cm_update_subscriber for updating existing subscribers. The description lacks explicit context or exclusion criteria.

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