kit_update_subscriber

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

With no annotations, the description fails to disclose key behavioral traits: idempotency, error handling for missing subscriber_id, what happens if the subscriber does not exist, or whether the update is partial or full. Minimal behavioral context is provided.

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 (4 words), but it sacrifices informativeness. While short, it does not front-load critical context. A few more sentences would improve utility without losing conciseness.

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?

Given the tool has 4 parameters (including a nested object), no output schema, and no annotations, the description is inadequate. It does not explain the overall purpose, required fields beyond the schema, or what the tool returns.

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 description coverage is 100%, so each parameter has a basic description. However, the tool description adds no additional meaning beyond the schema (e.g., explaining how 'fields' relates to custom fields or the update semantics). Baseline of 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 'Update an existing subscriber' clearly states the action and resource, but it does not differentiate from sibling update tools like kit_update_broadcast or kit_update_tag. It lacks specificity about what aspects of a subscriber are updatable.

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 such as kit_create_subscriber or other update tools. The description does not mention prerequisites or context.

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